Tdd uplink/downlink re-configuration mechanism

ABSTRACT

The invention relates to methods for communicating within a communication system when re-configured from a source to a target uplink/downlink configuration. The invention is also providing mobile station for performing these methods, and computer readable media the instructions of which cause the mobile station to perform the methods described herein. Specifically, the invention suggests to perform PUSCH transmissions in response to Downlink Control Information, DCI, transmissions such that the source uplink/downlink configuration is applied to PUSCH transmissions relating to DCI transmissions received up to and including subframe N−6, a predefined uplink/downlink configuration is applied to PUSCH transmissions relating to DCI transmissions received during subframes N−5 to N−1; and the target uplink/downlink configuration is applied to PUSCH transmissions relating to DCI transmissions received from subframe N onward.

FIELD OF THE INVENTION

The invention relates to methods for communication between a mobilestation and a base station based on a flexible TDD uplink downlinkconfiguration. The invention is also providing the mobile station andthe base station for participating in the methods described herein.

TECHNICAL BACKGROUND Long Term Evolution (LTE)

Third-generation mobile systems (3G) based on WCDMA radio-accesstechnology is being deployed on a broad scale all around the world. Afirst step in enhancing or evolving this technology entails introducingHigh-Speed Downlink Packet Access (HSDPA) and an enhanced uplink, alsoreferred to as High Speed Uplink Packet Access (HSUPA), giving a radioaccess technology that is highly competitive.

In order to be prepared for further increasing user demands and to becompetitive against new radio access technologies, 3GPP introduced a newmobile communication system which is called Long Term Evolution (LTE).LTE is designed to meet the carrier needs for high speed data and mediatransport as well as high capacity voice support for the next decade.The ability to provide high bit rates is a key measure for LTE.

The work item (WI) specification on Long-Term Evolution (LTE) calledEvolved UMTS Terrestrial Radio Access (UTRA) and UMTS Terrestrial RadioAccess Network (UTRAN) is finalized as Release 8 (LTE Rel. 8). The LTEsystem represents efficient packet-based radio access and radio accessnetworks that provide full IP-based functionalities with low latency andlow cost. In LTE, scalable multiple transmission bandwidths arespecified such as 1.4, 3.0, 5.0, 10.0, 15.0, and 20.0 MHz, in order toachieve flexible system deployment using a given spectrum. In thedownlink, Orthogonal Frequency Division Multiplexing (OFDM) based radioaccess was adopted because of its inherent immunity to multipathinterference (MPI) due to a low symbol rate, the use of a cyclic prefix(CP) and its affinity to different transmission bandwidth arrangements.Single-carrier frequency division multiple access (SC-FDMA) based radioaccess was adopted in the uplink, since provisioning of wide areacoverage was prioritized over improvement in the peak data rateconsidering the restricted transmit power of the user equipment (UE).Many key packet radio access techniques are employed includingmultiple-input multiple-output (MIMO) channel transmission techniquesand a highly efficient control signaling structure is achieved in LTERel. 8/9.

LTE Architecture

The overall architecture is shown in FIG. 1 and a more detailedrepresentation of the E-UTRAN architecture is given in FIG. 2. TheE-UTRAN consists of an eNodeB, providing the E-UTRA user plane(PDCP/RLC/MAC/PHY) and control plane (RRC) protocol terminations towardsthe user equipment (UE). The eNodeB (eNB) hosts the Physical (PHY),Medium Access Control (MAC), Radio Link Control (RLC) and Packet DataControl Protocol (PDCP) layers that include the functionality ofuser-plane header-compression and encryption. It also offers RadioResource Control (RRC) functionality corresponding to the control plane.It performs many functions including radio resource management,admission control, scheduling, enforcement of negotiated uplink Qualityof Service (QoS), cell information broadcast, ciphering/deciphering ofuser and control plane data, and compression/decompression ofdownlink/uplink user plane packet headers. The eNodeBs areinterconnected with each other by means of the X2 interface.

The eNodeBs are also connected by means of the S1 interface to the EPC(Evolved Packet Core), more specifically to the MME (Mobility ManagementEntity) by means of the S1-MME and to the Serving Gateway (SGW) by meansof the S1-U. The S1 interface supports a many-to-many relation betweenMMEs/Serving Gateways and eNodeBs. The SGW routes and forwards user datapackets, while also acting as the mobility anchor for the user planeduring inter-eNodeB handovers and as the anchor for mobility between LTEand other 3GPP technologies (terminating S4 interface and relaying thetraffic between 2G/3G systems and PDN GW). For idle state userequipments, the SGW terminates the downlink data path and triggerspaging when downlink data arrives for the user equipment. It manages andstores user equipment contexts, e.g. parameters of the IP bearerservice, network internal routing information. It also performsreplication of the user traffic in case of lawful interception.

The MME is the key control-node for the LTE access-network. It isresponsible for idle mode user equipment tracking and paging procedureincluding retransmissions. It is involved in the beareractivation/deactivation process and is also responsible for choosing theSGW for a user equipment at the initial attach and at time of intra-LTEhandover involving Core Network (CN) node relocation. It is responsiblefor authenticating the user (by interacting with the HSS). TheNon-Access Stratum (NAS) signaling terminates at the MME and it is alsoresponsible for generation and allocation of temporary identities touser equipments. It checks the authorization of the user equipment tocamp on the service provider's Public Land Mobile Network (PLMN) andenforces user equipment roaming restrictions. The MME is the terminationpoint in the network for ciphering/integrity protection for NASsignaling and handles the security key management. Lawful interceptionof signaling is also supported by the MME. The MME also provides thecontrol plane function for mobility between LTE and 2G/3G accessnetworks with the S3 interface terminating at the MME from the SGSN. TheMME also terminates the S6a interface towards the home HSS for roaminguser equipments.

Component Carrier Structure in LTE (Release 8)

The downlink component carrier of a 3GPP LTE (Release 8 and further) issubdivided in the time-frequency domain in so-called subframes. In 3GPPLTE (Release 8 and further) each subframe is divided into two downlinkslots as shown in FIG. 3, wherein the first downlink slot comprises thecontrol channel region (PDCCH region) within the first OFDM symbols.Each subframe consists of a give number of OFDM symbols in the timedomain (12 or 14 OFDM symbols in 3GPP LTE, Release 8 and further),wherein each OFDM symbol spans over the entire bandwidth of thecomponent carrier. The OFDM symbols thus each consists of a number ofmodulation symbols transmitted on respective N_(RB) ^(DL)×N_(sc) ^(RB)subcarriers as also shown in FIG. 4.

Assuming a multi-carrier communication system, e.g. employing OFDM, asfor example used in 3GPP Long Term Evolution (LTE), the smallest unit ofresources that can be assigned by the scheduler is one “resource block”.A physical resource block (PRB) is defined as N_(symb) ^(DL) consecutiveOFDM symbols in the time domain (e.g. 7 OFDM symbols) and N_(sc) ^(RB)consecutive subcarriers in the frequency domain as exemplified in FIG. 4(e.g. 12 subcarriers for a component carrier). In 3GPP LTE (Release 8),a physical resource block thus consists of N_(symb) ^(DL)×N_(sc) ^(RB)resource elements, corresponding to one slot in the time domain and 180kHz in the frequency domain (for further details on the downlinkresource grid, see for example 3GPP TS 36.211, “Evolved UniversalTerrestrial Radio Access (E-UTRA); Physical Channels and Modulation(Release 8)”, section 6.2, available at http://www.3gpp.org andincorporated herein by reference).

One subframe consists of two slots, so that there are 14 OFDM symbols ina subframe when a so-called “normal” CP (cyclic prefix) is used, and 12OFDM symbols in a subframe when a so-called “extended” CP is used. Forsake of terminology, in the following the time-frequency resourcesequivalent to the same N_(sc) ^(RB) consecutive subcarriers spanning afull subframe is called a “resource block pair”, or equivalent “RB pair”or “PRB pair”.

The term “component carrier” refers to a combination of several resourceblocks in the frequency domain. In subsequent releases of LTE, the term“component carrier” is no longer used; instead, the terminology ischanged to “cell”, which refers to a combination of downlink andoptionally uplink resources. The linking between the carrier frequencyof the downlink resources and the carrier frequency of the uplinkresources is indicated in the system information transmitted on thedownlink resources.

Similar assumptions for the component carrier structure apply to laterreleases too.

Logical and Transport Channels

The MAC layer provides a data transfer service for the RLC layer throughlogical channels. Logical channels are either Control Logical Channelswhich carry control data such as RRC signalling, or Traffic LogicalChannels which carry user plane data. Broadcast Control Channel (BCCH),Paging Control channel (PCCH), Common Control Channel (CCCH), MulticastControl Channel (MCCH) and Dedicated Control Channel (DCCH) are ControlLogical Channels. Dedicated Traffic channel (DTCH) and Multicast TrafficChannel (MTCH) are Traffic Logical Channels.

Data from the MAC layer is exchanged with the physical layer throughTransport Channels. Data is multiplexed into transport channelsdepending on how it is transmitted over the air. Transport channels areclassified as downlink or uplink as follows. Broadcast Channel (BCH),Downlink Shared Channel (DL-SCH), Paging Channel (PCH) and MulticastChannel (MCH) are downlink transport channels, whereas the Uplink SharedChannel (UL-SCH) and the Random Access Channel (RACH) are uplinktransport channels.

A multiplexing is then performed between logical channels and transportchannels in the downlink and uplink respectively.

Layer 1/Layer 2 (L1/L2) Control Signaling

In order to inform the scheduled users about their allocation status,transport format and other data-related information (e.g. HARQinformation, transmit power control (TPC) commands), L1/L2 controlsignaling is transmitted on the downlink along with the data. L1/L2control signaling is multiplexed with the downlink data in a subframe,assuming that the user allocation can change from subframe to subframe.It should be noted that user allocation might also be performed on a TTI(Transmission Time Interval) basis, where the TTI length can be amultiple of the subframes. The TTI length may be fixed in a service areafor all users, may be different for different users, or may even bydynamic for each user. Generally, the L1/2 control signaling needs onlybe transmitted once per TTI. Without loss of generality, the followingassumes that a TTI is equivalent to one subframe.

The L1/L2 control signaling is transmitted on the Physical DownlinkControl Channel (PDCCH). A PDCCH carries a message as a Downlink ControlInformation (DCI), which in most cases includes resource assignments andother control information for a mobile terminal or groups of UEs. Ingeneral, several PDCCHs can be transmitted in one subframe.

It should be noted that in 3GPP LTE, assignments for uplink datatransmissions, also referred to as uplink scheduling grants or uplinkresource assignments, are also transmitted on the PDCCH.

Generally, the information sent on the L1/L2 control signaling forassigning uplink or downlink radio resources (particularly LTE(-A)Release 10) can be categorized to the following items:

-   -   User identity, indicating the user that is allocated. This is        typically included in the checksum by masking the CRC with the        user identity;    -   Resource allocation information, indicating the resources        (Resource Blocks, RBs) on which a user is allocated. Note, that        the number of RBs on which a user is allocated can be dynamic;    -   Carrier indicator, which is used if a control channel        transmitted on a first carrier assigns resources that concern a        second carrier, i.e. resources on a second carrier or resources        related to a second carrier;    -   Modulation and coding scheme that determines the employed        modulation scheme and coding rate;    -   HARQ information, such as a new data indicator (NDI) and/or a        redundancy version (RV) that is particularly useful in        retransmissions of data packets or parts thereof;    -   Power control commands to adjust the transmit power of the        assigned uplink data or control information transmission;    -   Reference signal information such as the applied cyclic shift        and/or orthogonal cover code index, which are to be employed for        transmission or reception of reference signals related to the        assignment;    -   Uplink or downlink assignment index that is used to identify an        order of assignments, which is particularly useful in TDD        systems;    -   Hopping information, e.g. an indication whether and how to apply        resource hopping in order to increase the frequency diversity;    -   CSI request, which is used to trigger the transmission of        channel state information in an assigned resource; and    -   Multi-cluster information, which is a flag used to indicate and        control whether the transmission occurs in a single cluster        (contiguous set of RBs) or in multiple clusters (at least two        non-contiguous sets of contiguous RBs). Multi-cluster allocation        has been introduced by 3GPP LTE-(A) Release 10.

It is to be noted that the above listing is non-exhaustive, and not allmentioned information items need to be present in each PDCCHtransmission depending on the DCI format that is used.

Downlink control information occurs in several formats that differ inoverall size and also in the information contained in its fields. Thedifferent DCI formats that are currently defined for LTE are as followsand described in detail in 3GPP TS 36.212, “Multiplexing and channelcoding”, section 5.3.3.1 (available at http://www.3gpp.org andincorporated herein by reference). For further information regarding theDCI formats and the particular information that is transmitted in theDCI, please refer to the technical standard or to LTE—The UMTS Long TermEvolution—From Theory to Practice, Edited by Stefanie Sesia, IssamToufik, Matthew Baker, Chapter 9.3, incorporated herein by reference.

Format 0: DCI Format 0 is used for the transmission of resource grantsfor the PUSCH, using single-antenna port transmissions in uplinktransmission mode 1 or 2.Format 1: DCI Format 1 is used for the transmission of resourceassignments for single codeword PDSCH transmissions (downlinktransmission modes 1, 2 and 7).Format 1A: DCI Format 1A is used for compact signaling of resourceassignments for single codeword PDSCH transmissions, and for allocatinga dedicated preamble signature to a mobile terminal for contention-freerandom access.Format 1B: DCI Format 1B is used for compact signaling of resourceassignments for PDSCH transmissions using closed loop precoding withrank-1 transmission (downlink transmission mode 6). The informationtransmitted is the same as in Format 1A, but with the addition of anindicator of the precoding vector applied for the PDSCH transmission.Format 1C: DCI Format 1C is used for very compact transmission of PDSCHassignments. When format 1C is used, the PDSCH transmission isconstrained to using QPSK modulation. This is used, for example, forsignaling paging messages and broadcast system information messages.Format 1D: DCI Format 1D is used for compact signaling of resourceassignments for PDSCH transmission using multi-user MIMO. Theinformation transmitted is the same as in Format 1B, but instead of oneof the bits of the precoding vector indicators, there is a single bit toindicate whether a power offset is applied to the data symbols. Thisfeature is needed to show whether or not the transmission power isshared between two UEs. Future versions of LTE may extend this to thecase of power sharing between larger numbers of UEs.Format 2: DCI Format 2 is used for the transmission of resourceassignments for PDSCH for closed-loop MIMO operation.Format 2A: DCI Format 2A is used for the transmission of resourceassignments for PDSCH for open-loop MIMO operation. The informationtransmitted is the same as for Format 2, except that if the eNodeB hastwo transmit antenna ports, there is no precoding information, and forfour antenna ports two bits are used to indicate the transmission rank.Format 2B: Introduced in Release 9 and is used for the transmission ofresource assignments for PDSCH for dual-layer beamforming.Format 2C: Introduced in Release 10 and is used for the transmission ofresource assignments for PDSCH for closed-loop single-user or multi-userMIMO operation with up to 8 layers.Format 2D: has been introduced in Release 11 and is used for up to 8layer transmissions; mainly used for COMP (Cooperative Multipoint).Format 3 and 3A: DCI formats 3 and 3A are used for the transmission ofpower control commands for PUCCH and PUSCH with 2-bit or 1-bit poweradjustments respectively. These DCI formats contain individual powercontrol commands for a group of UEs.Format 4: DCI format 4 is used for the scheduling of the PUSCH, usingclosed-loop spatial multiplexing transmissions in uplink transmissionmode 2.

The following table gives an overview of some available DCI formats andthe typical number of bits, assuming for illustration purposes a systembandwidth of 50 RBs and four antennas at the eNodeB. The number of bitsindicated in the right column include the bits for the CRC of theparticular DCI.

TABLE DCI Formats Number of bits DCI including format Purpose CRC 0PUSCH grants 43 1 PDSCH assignments with a single codeword 47 1A PDSCHassignments using a compact format 43 1B PDSCH assignments for rank-1transmission 46 1C PDSCH assignments using a very compact format 29 1DPDSCH assignments for multi-user MIMO 46 2 PDSCH assignments forclosed-loop MIMO 62 operation 2A PDSCH assignments for open-loop 58 MIMOoperation 2B PDSCH assignments for dual-layer beamforming 57 2C PDSCHassignments for closed-loop single-user or 58 multiuser MIMO operation2D PDSCH assignments for closed-loop single- 61 user or multi-user MIMOoperation, COMP 3 Transmit Power Control (TPC) commands for 43 multipleusers for PUCCH and PUSCH with 2-bit power adjustments 3A Transmit PowerControl (TPC) commands for 43 multiple users for PUCCH and PUSCH with1-bit power adjustments 4 PUSCH grants 52

In order that the UE can identify whether it has received a PDCCHtransmission correctly, error detection is provided by means of a 16-bitCRC appended to each PDCCH (i.e. DCI). Furthermore, it is necessary thatthe UE can identify which PDCCH(s) are intended for it. This could intheory be achieved by adding an identifier to the PDCCH payload;however, it turns out to be more efficient to scramble the CRC with the“UE identity”, which saves the additional overhead. The CRC may becalculated and scrambled as defined in detail by 3GPP in TS 36.212,Section 5.3.3.2 “CRC attachment”, incorporated hereby by reference. Thesection describes how error detection is provided on DCI transmissionsthrough a Cyclic Redundancy Check (CRC). A brief summary is given below.

The entire payload is used to calculate the CRC parity bits. The paritybits are computed and attached. In the case where UE transmit antennaselection is not configured or applicable, after attachment, the CRCparity bits are scrambled with the corresponding RNTI.

The scrambling may further depend on the UE transmit antenna selection,as apparent from TS 36.212. In the case where UE transmit antennaselection is configured and applicable, after attachment, the CRC paritybits are scrambled with an antenna selection mask and the correspondingRNTI. As in both cases the RNTI is involved in the scrambling operation,for simplicity and without loss of generality the following descriptionof the embodiments simply refers to the CRC being scrambled (anddescrambled, as applicable) with an RNTI, which should therefore beunderstood as notwithstanding e.g. a further element in the scramblingprocess such as an antenna selection mask.

Correspondingly, the UE descrambles the CRC by applying the “UEidentity” and, if no CRC error is detected, the UE determines that PDCCHcarries its control information intended for itself. The terminology of“masking” and “de-masking” is used as well, for the above-describedprocess of scrambling a CRC with an identity.

The “UE identity” mentioned above with which the CRC of the DCI may bescrambled can also be a SI-RNTI (System Information Radio NetworkTemporary Identifier), which is not a “UE identity” as such, but ratheran identifier associated with the type of information that is indicatedand transmitted, in this case the system information. The SI-RNTI isusually fixed in the specification and thus known a priori to all UEs.

There are various types of RNTIs that are used for different purposes.The following tables taken from 3GPP 36.321 Chapter 7.1 shall give anoverview of the various 16-bits RNTIs and their usages.

TABLE RNTIs Value (hexa-decimal) RNTI 0000 N/A 0001-003C RA-RNTI,C-RNTI, Semi-Persistent Scheduling C-RNTI, Temporary C-RNTI,TPC-PUCCH-RNTI and TPC-PUSCH-RNTI (see note) 003D-FFF3 C-RNTI,Semi-Persistent Scheduling C-RNTI, Temporary C-RNTI, TPC-PUCCH-RNTI andTPC-PUSCH-RNTI FFF4-FFFC Reserved for future use FFFD M-RNTI FFFE P-RNTIFFFF SI-RNTI

Physical Downlink Control Channel (PDCCH) and Physical Downlink SharedChannel (PDSCH)

The physical downlink control channel (PDCCH) carries e.g. schedulinggrants for allocating resources for downlink or uplink datatransmission. Multiple PDCCHs can be transmitted in a subframe.

The PDCCH for the user equipments is transmitted on the first N_(symb)^(PDCCH) OFDM symbols (usually either 1, 2 or 3 OFDM symbols asindicated by the PCFICH, in exceptional cases either 2, 3, or 4 OFDMsymbols as indicated by the PCFICH) within a subframe, extending overthe entire system bandwidth; the system bandwidth is typicallyequivalent to the span of a cell or component carrier. The regionoccupied by the first N_(symb) ^(PDCCH) OFDM symbols in the time domainand the N_(RB) ^(DL)×N_(sc) ^(RB) subcarriers in the frequency domain isalso referred to as PDCCH region or control channel region. Theremaining N_(symb) ^(PDSCH)=2·N_(symb) ^(DL)−N_(symb) ^(PDCCH) OFDMsymbols in the time domain on the N_(RB) ^(DL)×N_(sc) ^(RB) subcarriersin the frequency domain is referred to as the PDSCH region or sharedchannel region (see below).

For a downlink grant (i.e. resource assignment) on the physical downlinkshared channel (PDSCH), the PDCCH assigns a PDSCH resource for (user)data within the same subframe. The PDCCH control channel region within asubframe consists of a set of CCE where the total number of CCEs in thecontrol region of subframe is distributed throughout time and frequencycontrol resource. Multiple CCEs can be combined to effectively reducethe coding rate of the control channel. CCEs are combined in apredetermined manner using a tree structure to achieve different codingrate.

On a transport channel level, the information transmitted via the PDCCHis also referred to as L1/L2 control signaling (for details on L1/L2control signaling see above).

There is a particular predefined timing relation between uplink resourceassignments received in a subframe and the corresponding uplinktransmission in PUSCH. Details are given in TS 36.213 v11.1.0 “3rdGeneration Partnership Project; Technical Specification Group RadioAccess Network; Evolved Universal Terrestrial Radio Access (E-UTRA);Physical layer procedures (Release 11)” Chapter 8.0 “UE procedure fortransmitting the physical uplink shared channel” incorporated herewithby reference.

In particular, Table 8-2 of TS 36.213 which is reproduced in FIG. 7defines the parameter k for the TDD configurations 0-6, where kindicates the positive offset of the target of an uplink resourceallocation received in a subframe; for TDD configuration 0 there isadditional definition of the timing for uplink subframes 3 and 8,omitted herewith for simplicity. For instance, the parameter k is 6 forsubframe 1 of TDD configuration 1, meaning that an uplink resourceallocation received in subframe 1 of TDD configuration 1 is intended forsubframe 1+6=7 of TDD configuration 1, which indeed is an uplinksubframe, etc.

Hybrid ARQ Schemes

A common technique for error detection and correction in packettransmission systems over unreliable channels is called hybrid AutomaticRepeat request (HARQ). Hybrid ARQ is a combination of Forward ErrorCorrection (FEC) and ARQ.

If a FEC encoded packet is transmitted and the receiver fails to decodethe packet correctly (errors are usually checked by a CRC (CyclicRedundancy Check)), the receiver requests a retransmission of thepacket. Generally (and throughout this document) the transmission ofadditional information is called “retransmission (of a packet)”,although this retransmission does not necessarily mean a transmission ofthe same encoded information, but could also mean the transmission ofany information belonging to the packet (e.g. additional redundancyinformation).

Depending on the information (generally code-bits/symbols), of which thetransmission is composed, and depending on how the receiver processesthe information, the following Hybrid ARQ schemes are defined:

In Type I HARQ schemes, the information of the encoded packet isdiscarded and a retransmission is requested, if the receiver fails todecode a packet correctly. This implies that all transmissions aredecoded separately. Generally, retransmissions contain identicalinformation (code-bits/symbols) to the initial transmission.

In Type II HARQ schemes, a retransmission is requested, if the receiverfails to decode a packet correctly, where the receiver stores theinformation of the (erroneously received) encoded packet as softinformation (soft-bits/symbols). This implies that a soft-buffer isrequired at the receiver. Retransmissions can be composed out ofidentical, partly identical or non-identical information(code-bits/symbols) according to the same packet as earliertransmissions. When receiving a retransmission the receiver combines thestored information from the soft-buffer and the currently receivedinformation and tries to decode the packet based on the combinedinformation. (The receiver can also try to decode the transmissionindividually, however generally performance increases when combiningtransmissions.) The combining of transmissions refers to so-calledsoft-combining, where multiple received code-bits/symbols are likelihoodcombined and solely received code-bits/symbols are code combined. Commonmethods for soft-combining are Maximum Ratio Combining (MRC) of receivedmodulation symbols and log-likelihood-ratio (LLR) combining (LLR combingonly works for code-bits).

Type II schemes are more sophisticated than Type I schemes, since theprobability for correct reception of a packet increases with everyreceived retransmission. This increase comes at the cost of a requiredhybrid ARQ soft-buffer at the receiver. This scheme can be used toperform dynamic link adaptation by controlling the amount of informationto be retransmitted. E.g. if the receiver detects that decoding has been“almost” successful, it can request only a small piece of informationfor the next retransmission (smaller number of code-bits/symbols than inprevious transmission) to be transmitted. In this case it might happenthat it is even theoretically not possible to decode the packetcorrectly by only considering this retransmission by itself(non-self-decodable retransmissions).

Type III HARQ schemes may be considered a subset of Type II schemes: Inaddition to the requirements of a Type II scheme each transmission in aType III scheme must be self-decodable.

Synchronous HARQ means that the re-transmissions of HARQ blocks occur atpre-defined periodic intervals. Hence, no explicit signaling is requiredto indicate to the receiver the retransmission schedule.

Asynchronous HARQ offers the flexibility of scheduling re-transmissionsbased on air interface conditions. In this case some identification ofthe HARQ process needs to be signaled in order to allow for a correctcombining and protocol operation. In 3GPP LTE systems, HARQ operationswith eight processes are used. The HARQ protocol operation for downlinkdata transmission will be similar or even identical to HSDPA.

In uplink HARQ protocol operation there are two different options on howto schedule a retransmission. Retransmissions are either “scheduled” bya NACK (also referred to as a synchronous non-adaptive retransmission)or are explicitly scheduled by the network by transmitting a PDCCH (alsoreferred to as synchronous adaptive retransmissions). In case of asynchronous non-adaptive retransmission the retransmission will use thesame parameters as the previous uplink transmission, i.e. theretransmission will be signaled on the same physical channel resources,respectively uses the same modulation scheme/transport format.

Since synchronous adaptive retransmissions are explicitly scheduled viaPDCCH, the eNodeB has the possibility to change certain parameters forthe retransmission. A retransmission could be for example scheduled on adifferent frequency resource in order to avoid fragmentation in theuplink, or eNodeB could change the modulation scheme or alternativelyindicate to the user equipment what redundancy version to use for theretransmission. It should be noted that the HARQ feedback (ACK/NACK) andPDCCH signaling occurs at the same timing. Therefore the user equipmentonly needs to check once whether a synchronous non-adaptiveretransmission is triggered (i.e. only a NACK is received) or whethereNode B requests a synchronous adaptive retransmission (i.e. PDCCH issignaled).

HARQ and Control Signaling for TDD Operation

As explained above, transmission of downlink or uplink data with HARQrequires that ACKnowledgements (ACK or Negative ACK) be sent in theopposite direction to inform the transmitting side of the success orfailure of the packet reception.

In case of FDD operation, acknowledgement indicators related to datatransmission in a subframe n are transmitted in the opposite directionduring subframe n+4, such that a one-to-one synchronous mapping existsbetween the instant at which the transport is transmitted and itscorresponding acknowledgment. However, in the case of TDD operation,subframes are designated on a cell-specific basis as uplink or downlinkor special (see next chapter), thereby constraining the times at whichresource grants, data transmissions, acknowledgments and retransmissionscan be sent in their respective directions. The LTE design for TDDtherefore supports grouped ACK/NACK transmission to carry multipleacknowledgements within one subframe.

For uplink HARQ, the sending (in one downlink subframe) of multipleacknowledgements on the Physical Hybrid ARQ Indicator CHannel (PHICH) isnot problematic since, when viewed from the eNodeB, this is notsignificantly different from the case in which single acknowledgementsare sent simultaneously to multiple UEs. However, for downlink HARQ, ifthe asymmetry is downlink-biased, the uplink control signaling (PUCCH)formats of FDD are insufficient to carry the additional ACK/NACKinformation. Each of the TDD subframe configurations in LTE (see below,and FIG. 5) has its own such mapping predefined between downlink anduplink subframes for HARQ purposes, with the mapping being designed toachieve a balance between minimization of acknowledgment delay and aneven distribution of ACK/NACKs across the available uplink subframes.Further details are provided in TS 36.213 v11.1.0 “3rd GenerationPartnership Project; Technical Specification Group Radio Access Network;Evolved Universal Terrestrial Radio Access (E-UTRA); Physical layerprocedures (Release 11)” Chapter 7.3 incorporated herewith by reference.

TS 36.213 v11.1.0 “3rd Generation Partnership Project; TechnicalSpecification Group Radio Access Network; Evolved Universal TerrestrialRadio Access (E-UTRA); Physical layer procedures (Release 11)” Chapter10.1.3, incorporated herein by reference explains the TDD HARQ-ACKfeedback procedure.

Table 10.1.3-1 of TS 36.213 which is reproduced in FIG. 6 gives thedownlink association set index for the ACK/NACK/DTX responses for thesubframes of a radio frame, wherein the number in the boxes for the TDDconfigurations indicates the negative offset of the subframe which HARQfeedback is transported in said subframe. For instance, subframe 9 forTDD configuration 0 transports the HARQ feedback of subframe 9−4=5;subframe 5 of TDD configuration 0 being indeed a downlink subframe (seeFIG. 5).

In HARQ operation, the eNB can transmit different coded version from theoriginal TB in retransmissions so that the UE can employ incrementalredundancy (IR) combining [8] to get additional coding gain over thecombining gain. However in realistic systems, it is possible that theeNB transmits a TB to one specific UE on one resource segment, but theUE can not detect the data transmission due to DL control informationlost. In this case, IR combining will lead to very poor performance fordecoding the retransmissions because the systematic data has not beenavailable at the UE. To mitigate this problem the UE should feed back athird state, namely discontinuous transmission (DTX) feedback, toindicate that no TB is detected on the associated resource segment(which is different from NACK indicating the decoding failure).

Time Division Duplex—TDD

LTE can operate in Frequency-Division-Duplex (FDD) andTime-Division-Duplex (TDD) modes in a harmonized framework, designedalso to support the evolution of TD-SCDMA (Time-Division SynchronousCode Division Multiple Access). TDD separates the uplink and downlinktransmissions in the time domain, while the frequency may stay the same.

The term “duplex” refers to bidirectional communication between twodevices, distinct from unidirectional communication. In thebidirectional case, transmissions over the link in each direction maytake place at the same time (“full duplex”) or at mutually exclusivetimes (“half duplex”).

For TDD in the unpaired radio spectrum, the basic structure of RBs andREs is depicted in FIG. 4, but only a subset of the subframes of a radioframe are available for downlink transmissions; the remaining subframesare used for uplink transmissions, or for special subframes. Specialsubframes are important to allow uplink transmission timings to beadvanced, so as to make sure that transmitted signals from the UEs (i.e.uplink) arrive roughly at the same time at the eNodeB. Since the signalpropagation delay is related to the distance between transmitter andreceiver (neglecting reflection and other similar effects), this meansthat a signal transmitted by a UE near the eNodeB travels for a shorttime than the signals transmitted by a UE far from the eNodeB. In orderto arrive at the same time, the far UE has to transmit its signalearlier than the near UE, which is solved by the so-called “timingadvance” procedure in 3GPP systems.

In TDD this has the additional circumstance that the transmission andreception occur on the same carrier frequency, i.e. downlink and uplinkneed to be duplexed in time domain. While a UE far from the eNodeB needsto start uplink transmission earlier than the near UE, conversely, adownlink signal is received by a near UE earlier than by the far UE. Inorder to be able to switch the circuitry from DL reception to ULtransmission, guard time is defined in the special subframe. Toadditionally take care of the timing advance problem, the guard time fora far UE needs to be longer than for a near UE.

This TDD structure is known as “Frame Structure Type 2” in 3GPP LTERelease 8 and later, of which seven different uplink-downlinkconfigurations are defined, which allow a variety of downlink-uplinkratios and switching periodicities. FIG. 5 illustrates the Table withthe 7 different TDD uplink-downlink configurations, indexed from 0-6,where “D” shall indicate a downlink subframe, “U” an uplink subframe and“S” a special subframe. As can be seen therefrom, the seven availableTDD uplink-downlink configurations can provide between 40% and 90% ofdownlink subframes (when, for simplicity, counting a special subframe asa downlink subframe, since part of such a subframe is available fordownlink transmission).

FIG. 5 shows the frame structure type 2, particularly for a 5 msswitch-point periodicity, i.e. for TDD configurations 0, 1, 2 and 6.

FIG. 8 illustrates a radio frame, being 10 ms in length, and thecorresponding two half-frames of 5 ms each. The radio frame consists of10 subframes with each 1 ms, where each of the subframes is assigned thetype of uplink, downlink or special, as defined by one of theUplink-downlink configurations according to the table of FIG. 5.

As can be appreciated from FIG. 5, subframe #1 is always a Specialsubframe, and subframe #6 is a Special subframe for TDD configurations0, 1, 2 and 6; for TDD configurations 3, 4 and 5, subframe #6 isdestined for downlink. Special subframes include three fields: DwPTS(Downlink Pilot Time Slot), the GP (Guard Period) and UpPTS (UplinkPilot Time Slot). The following Table shows information on the specialsubframe and in particular lists the lengths of DwPTS (Downlink PilotTime Slot), the GP (Guard Period) and of UpPTS (Uplink Pilot Time Slot)as a multiple of the sample time T_(s)=(1/30720) ms as defined for 3GPPLTE Release 11.

TABLE special subframe configurations, Frame Structure Type 2 Normalcyclic prefix in downlink Extended cyclic prefix in downlink UpPTS UpPTSSpecial Normal Extended Normal Extended subframe cyclic prefix cyclicprefix cyclic prefix cyclic prefix configuration DwPTS in uplink inuplink DwPTS in uplink in uplink 0  6592 · T_(s) 2192 · T_(s) 2560 ·T_(s)  7680 · T_(s) 2192 · T_(s) 2560 · T_(s) 1 19760 · T_(s) 20480 ·T_(s) 2 21952 · T_(s) 23040 · T_(s) 3 24144 · T_(s) 25600 · T_(s) 426336 · T_(s)  7680 · T_(s) 4384 · T_(s) 5120 · T_(s) 5  6592 · T_(s)4384 · T_(s) 5120 · T_(s) 20480 · T_(s) 6 19760 · T_(s) 23040 · T_(s) 721952 · T_(s) 12800 · T_(s) 8 24144 · T_(s) — — — 9 13168 · T_(s) — — —

The TDD configuration applied in the system has an impact on manyoperations performed at the mobile station and base station, such asradio resource management (RRM) measurements, channel state information(CSI) measurements, channel estimations, PDCCH detection and HARQtimings.

In particular, the UE reads the system information to learn about theTDD configuration in its current cell, i.e. which subframe to monitorfor measurement, for CSI measure and report, for time domain filteringto get channel estimation, for PDCCH detection, or for UL/DL ACK/NACKfeedback.

Shortcoming of Current Semi-Static TDD UL/DL Configuration Scheme

The current mechanism for adapting UL-DL allocation is based on thesystem information acquisition procedure or the system informationchange procedure, where the particular UL-DL TDD configuration isindicated by a SIB, in this case/specifically by the TDD-configparameter in SIB1 (for details on the broadcast of system information,3GPP TS 25.331, “Radio Resource Control (RRC)”, version 6.7.0, section8.1.1, incorporated herein by reference).

In the system information change procedure as specified in LTE Release8, the supported time scale for a TDD UL/DL re-configuration is every640 ms or longer. When re-using the ETWS (Earthquake and Tsunami WarningSystem), the supported time scale for UL-DL TDD re-configuration isevery 320 ms or longer depending on the configured default paging cycle.

Nevertheless, the semi-static allocation of TDD UL/DL configuration mayor may not reflect the instantaneous traffic situation. In case of rapidchanges between an uplink-dominated to a downlink-dominated trafficsituation, the system information change procedure is too slow for adynamic TDD UL/DL re-configuration. Accordingly, the semi-static TDDUL/DL re-configuration is too slow to maximize the subframe utilizationwith respect to the instantaneous traffic situation.

In this respect, a dynamic TDD UL/DL re-configuration has been widelydiscussed in connection with LTE Release 12. The dynamic TDD UL/DLre-configuration is anticipated to adapt the TDD UL/DL configuration tothe current traffic needs, for instance, to dynamically create moredownlink subframes to increase the downlink bandwidth or to dynamicallycreate more blanck uplink subframes in order to mitigate interference tocommunications e.g. in uplink or downlink or to/from a neighboring cell.

In particular, LTE Release 12 will support an explicit signaling for thedynamic TDD UL/DL re-configuration. For this purpose, various signalingmechanisms are currently discussed. These signaling mechanisms shallenable instantaneous distribution of information on the TDD UL/DLre-configuration within the communication system and shall allow themobile station/base station to re-configure the TDD UL/DL configurationwithout delay.

It turns out that currently employed RRC signaling mechanisms cannotensure short TDD UL/DL re-configuration intervals as required to meetthe needs of a dynamic TDD UL/DL re-configuration. In this respect, itis currently expected that a DCI signaling mechanism will be defined toallow for the dynamic TDD UL/DL re-configuration. The re-configurationis assumed to be valid for at least one radio frame (i.e. 10 ms).

With the above defined system constraints, the dynamic TDD UL/DLre-configuration will have to overcome incompatibilities between DCI toPUSCH timing relations as well as PDSCH to HARQ-ACK timing relationsthat are defined for each of the TDD configurations.

As already described earlier, for each TDD configuration 0-6 a timingrelation is defined between an uplink resource allocation (e.g. ULgrant) in a DCI format 0/4 message and the corresponding target PUSCHtransmission in an uplink subframe. Specifically, the DCI to PUSCHtiming relation allows for target PUSCH transmissions to be scheduledthat are overlapping radio frame boundaries. In other words, a PUSCHtransmission and the relating DCI transmission may take place indifferent radio frames. For example, according to TDD configuration 6, aPUSCH transmission in subframe 2 in one radio frame relates to a DCItransmission that has taken place in the previous radio frame.

Similarly, for each TDD configuration 0-6 a timing relation is definedbetween one or plural PDSCH transmissions and one or plural subsequentHybrid ARQ-ACK transmissions. Also the PDSCH to HARQ-ACK timing relationallows for HARQ-ACK transmissions overlapping radio frame boundaries. Inother words, a HARQ-ACK transmission and the relating PDSCH transmissionmay take place in different radio frames. For example, according to TDDconfiguration 5, HARQ-ACK transmissions in subframe 2 for one radioframe relates to PDSCH transmissions that have taken place in theprevious two radio frames.

In this respect, for a TDD UL/DL re-configuration between subsequentsubframes the application of the corresponding DCI to PUSCH timingrelations does not allow for a continuous resource allocation of allsupported uplink subframes. The inconsistencies in the uplink resourceallocation shall be exemplified for the case where the UL grant is in aDCI transmission that is transmitted before the TDD re-configurationtakes effect and the PUSCH transmission relating to the DCI transmissionis scheduled after the TDD re-configuration takes effect.

Exemplarily, a TDD UL/DL re-configuration from TDD configuration 3 toTDD configuration 6 is illustrated in FIG. 9a . For each of the TDDconfiguration 3 and TDD configuration 6, the DCI to PUSCH timingrelations are indicated by dash-dotted arrows. Accordingly, forallocation of a PUSCH transmission (i.e. uplink transmission) in asubframe which supports uplink transmissions, a DCI transmissionrelating to the respective PUSCH transmission is indicated as the originof the dash-dotted arrow.

However, due to the TDD UL/DL re-configuration from TDD configuration 3to TDD configuration 6, a PUSCH transmission in the subframe with index24 is not possible. In particular, the TDD configuration 6, which is tobe used after the TDD UL/DL re-configuration takes effect (i.e. from andincluding the subframe with the index 20 onward), does not, in the DCIto PUSCH timing relation of TDD configuration 6, allow for a DCItransmission that could result in PUSCH transmission in the subframewith index 24. In FIG. 9a , this can be seen by the absence of arrow(s)terminating at the PUSCH of subframe 24.

Even when assuming that PUSCH transmissions relating to DCI transmissionbefore the TDD UL/DL re-configuration are to be carried out after theTDD UL/DL re-configuration, as for example indicated for the PUSCHtransmission in the subframes with index 22 and 23, there is nopossibility of a DCI transmission that would result in the scheduling ofa PUSCH transmission in the subframe with index 24.

Another example for the TDD UL/DL re-configuration from the TDDconfiguration 0 to TDD configuration 6 is illustrated in FIG. 10. Alsoin this example, there is no possibility of a DCI transmission thatwould result in the scheduling of a PUSCH transmission in the subframewith index 24.

Consequently, due to the DCI to PUSCH timing relation being predefinedfor each TDD configuration, the uplink bandwidth cannot be immediatelyutilized after TDD UL/DL re-configuration.

Further exemplarily, a TDD UL/DL re-configuration from TDD configuration3 to TDD configuration 6 is also illustrated in FIG. 9b . For each ofthe TDD configuration 3 and the TDD configuration 6 the PDSCH toHARQ-ACK timing relations are indicated by dash-dotted arrows.Accordingly, for HARQ-ACK transmissions in a subframe which supportsuplink transmissions, PDSCH transmissions relating to the respectiveHARQ-ACK transmissions are indicated as the origin of the dash-dottedarrow.

However, due to the TDD UL/DL re-configuration from TDD configuration 3to TDD configuration 6, a HARQ-ACK transmission for the PDSCHtransmissions in the subframe with indexes 11, 17 and 18 is notpossible. In particular, the TDD configuration 6, which is to be usedafter the TDD UL/DL re-configuration takes place (i.e. from andincluding the subframe with the index 20 onward), does not, in the PDSCHto HARQ-ACK timing relation of TDD configuration 6, allow for HARQ-ACKtransmissions relating to the PDSCH transmissions in the subframe withindexes 11, 17 and 18.

Even when assuming, that HARQ-ACK transmissions relating to PDSCHtransmissions before the TDD UL/DL re-configuration are to be carriedout after the TDD UL/DL re-configuration, as for example indicated forthe HARQ-ACK transmissions relating to the PDSCH transmission in thesubframes with index 15, 16 and 19, there is no possibility of HARQ-ACKtransmissions that would acknowledge the PDSCH transmissions in thesubframe with indexes 11, 17 and 18.

Consequently, due to the PDSCH to HARQ-ACK timing relation beingpredefined for each TDD configuration, the allocated Hybrid ARQfunctionality cannot be immediately utilized after TDD UL/DLre-configuration.

In recent 3GPP LTE meetings various approaches were discussed for TDDUL/DL re-configuration. Specifically, it was proposed to separatelydefine reference configurations for the DCI to PUSCH timing relations aswell as the PDSCH to HARQ-ACK timing relations that would have to becontinuously applied after TDD UL/DL re-configuration. Exemplarily, eventhough SIB1 TDD configuration is operated an UE would continuously applythe timing relation specified in the newly defined referenceconfiguration.

However, these approaches have the following drawbacks: Firstly, anadditional higher layer configuration is required. Secondly, referenceconfiguration timing relations would have to be applied even if they arenot (e.g. no longer) required.

In the exemplary case of the SIB1 TDD configuration, this results inunnecessarily long delays for some HARQ-ACK transmissions, in anunnecessary long delays between DCI an PUSCH transmissions from some TDDconfigurations, and in an unnecessary bundling/multiplexing of HARQ-ACKtransmissions into a few PUCCH subframes.

SUMMARY OF THE INVENTION

One object of the invention is to provide for an improved Time DivisionDuplex re-configuration operation, that solves the problems of the priorart as discussed above.

The object is solved by the subject matter of the independent claims.Advantageous embodiments are subject to the dependent claims.

The various embodiments of the invention are based on the concept thatfor a TDD UL/DL re-configuration the DCI to PUSCH and/or to PDSCH toHARQ-ACK timing relations are to be applied differently (i.e.separately) from the TDD radio frame configuration. This distinctionbetween the TDD radio frame configuration and the timing relations isonly to take place during a short period of time before and/or after there-configuration takes effect.

In particular, predefined TDD radio frame configurations or TDDconfigurations define the reservation of subframes within a radio frameas downlink (abbreviated “D”), uplink (abbreviated “U”), or special(abbreviated “S”) subframes. In this respect, in the event of a TDDUL/DL re-configuration, a source TDD configuration defines thereservation of subframes before the re-configuration takes effect and atarget TDD configuration defines the reservation of subframes after there-configuration takes effect.

It is important to note here that the reservation for downlink or uplinkonly serves to indicate the transmission/reception direction (i.e.downlink for transmissions from a base station to mobile stations,uplink for transmissions from mobile stations to a base station), anddoes not necessarily imply that such a transmission (e.g. on PDSCH for Dsubframes or on PUSCH for U subframes) actually occurs. In this respect,uplink transmissions can occur only in U subframes (or the UpPTS part ofan S subframe), but not every U (or UpPTS part of an S) subframenecessarily carries an uplink transmission. Likewise, downlinktransmissions can occur only in D subframes (or the DwPTS part of an Ssubframe), but not every D (or DwPTS part of an S) subframe necessarilycarries a downlink transmission.

Exemplarily, in the event of a TDD UL/DL re-configuration from sourceTDD configuration 3 to target TDD configuration 6, the source TDDconfiguration 3 defines the reservation of the subframes within radioframes before the re-configuration takes effect, and the target TDDconfiguration 6 defines the reservation of the subframes with radioframes after the re-configuration. In this respect, the TDDcommunication scheme utilizes the TDD configuration pattern “D, S, U, U,U, D, D, D, D, D” before and the TDD configuration pattern “D, S, U, U,U, D, S, U, U, D” after the re-configuration takes effect.

According to the invention, the DCI to PUSCH timing relations and/or thePDSCH to HARQ-ACK timing relations are applied differently from thesource/target TDD configuration during a time period before and/or afterthe TDD UL/DL re-configuration takes effect. In other words, even thougheach source/target TDD configuration prescribes a DCI to PUSCH timingrelation and/or a PDSCH to HARQ-ACK timing relation, according to theinvention this prescribed rule is broken for a short period of timebefore and/or after the TDD UL/DL re-configuration takes effect.

In particular, the term “DCI to PUSCH timing relation” defines when(i.e. during which subframe) PUSCH transmissions relating to DCItransmissions have to be carried out. Particularly, since PUSCHtransmissions require preceding UL grants, the DCI transmissions, towhich PUSCH transmissions relate, inherently are DCI transmissionscarrying an UL grant. In other words, in LTE Release 11 thecorresponding DCI transmissions are of Format 0/4.

Similarly, the term “PDSCH to HARQ-ACK timing relation” defines when(i.e. during which subframe) HARQ-ACK transmissions relating to PDSCHtransmissions have to be carried out. In the context of the invention,the term “HARQ-ACK transmission” refers to the transmission ofACK/NACK/DTX information related to one PDSCH transmission. In thisrespect, in case the following description should state that no HARQ-ACKtransmission is carried out in subframe 0 which relates to PDSCHtransmission in subframe P, this should be interpreted in the sense thatpotential HARQ-ACK transmissions in subframe 0 do not includeACK/NACK/DTX information related to PDSCH transmission P. In otherwords, it is possible that HARQ-ACK transmissions occur in subframe 0for PDSCH transmissions in subframes other than subframe P.

According to the invention, during the TDD UL/DL re-configuration thetiming relations that are predefined for TDD configurations and relateto DCI to PUSCH and/or to PDSCH to HARQ-ACK are to be applieddifferently from the TDD radio frame configuration in order to improvethe uplink bandwidth utilization and/or to enable Hybrid ARQfunctionality, respectively.

According to a first aspect of the invention, a communication between amobile station and a base station in a communication system is definedemploying the improved TDD UL/DL re-configuration. The communication isre-configured from a source TDD configuration to a target TDDconfiguration.

The source TDD configuration is one out of a subset of a plurality ofpre-configured TDD configurations. For example, the source TDDconfiguration is one out of the subset of TDD configurations 1-6, wherethe plurality of TDD configurations includes TDD configurations 0-6. Thetarget TDD configuration is any one out of the plurality ofpre-configured TDD configurations, for example any one out of TDDconfigurations 0-6.

In the event that the communication between the mobile station and thebase station is to be re-configured for a predetermined subframe N atthe beginning of a radio frame, the subframes before subframe N wherethe re-configuration takes effect is configured based on the source TDDconfiguration whereas the subframes from and including subframe N onwardare configured based on the target TDD configuration.

Additionally, in case the mobile station detects one or plural DownlinkControl Information, DCI, transmission(s) carrying an UL grant(s), themobile station performs one or plural Physical Uplink Shared Channel,PUSCH, transmissions in response to the detected DCI transmission(s)according to the following scheme:

For PUSCH transmissions relating to DCI transmissions that were receivedby the mobile station up to and including subframe N−6, the mobilestation applies the source TDD configuration. Specifically, the mobilestation applies the timing relation defined by the source TDDconfiguration for one or plural PUSCH transmission(s) that are scheduledin response to the one or plural DCI transmission(s) carrying therespective UL grant received during same subframes, thereby determiningwhen the one or plural PUSCH transmission(s) occur.

For PUSCH transmissions relating to DCI transmissions that were receivedby the mobile station during and including subframe N−5 to and includingsubframe N−1, the mobile station applies an intermediate (i.e.predefined) TDD configuration. Specifically, the mobile station appliesthe timing relation defined by the intermediate (i.e. predefined) TDDconfiguration for the one or plural PUSCH transmission(s) that arescheduled in response to the one or plural DCI transmission(s) carryingthe respective UL grant received during same subframes, therebydetermining when the one or plural PUSCH transmission(s) occur.

For PUSCH transmissions relating to DCI transmissions that were receivedby the mobile station from and including subframe N onward, the mobilestation applies the target TDD configuration. Specifically, the mobilestation applies the timing relation defined by the target TDDconfiguration for the one or plural PUSCH transmission(s) that arescheduled in response to the one or plural DCI transmission(s) carryingthe respective UL grant received during same subframes, therebydetermining when the one or plural PUSCH transmission(s) occur.

The intermediate (i.e. predefined) TDD configuration is one out of theplurality of pre-configured TDD configurations, for example any one outof TDD configurations 0-6.

In particular, due to the application of the intermediate (i.e.predefined) TDD configuration to PUSCH transmission(s) relating to theDCI transmissions immediately before the TDD UL/DL re-configuration (andthereby the target TDD configuration) takes effect, the uplink bandwidthutilization within the communication system can be improved.

According to a second aspect of the invention a communication between amobile station and a base station in a communication system is specifiedemploying a differently improved TDD UL/DL re-configuration. Thecommunication is re-configured from a source TDD configuration to atarget TDD configuration.

The source TDD configuration is a predefined one out of a plurality ofpre-configured TDD configurations. For example, the source TDDconfiguration is TDD configuration 0. The target TDD configuration isany one out of the plurality of pre-configured TDD configurations, forexample any one out of TDD configurations 0-6.

In the event that the communication between the mobile station and thebase station is to be re-configured for a predetermined subframe N atthe beginning of the subframe, the radio frames before subframe N wherethe re-configuration takes effect are configured based on the source TDDconfiguration whereas the radio frames from and including subframe Nonward are configured based on the target TDD configuration.

Further, in case the mobile station detects one or plural DownlinkControl Information, DCI, transmission(s) carrying UL grant(s), themobile station performs one or plural Physical Uplink Shared Channel,PUSCH, transmissions in response to the detected DCI transmission(s)according to the following scheme:

For PUSCH transmissions relating to DCI transmissions that were receivedby the mobile station up to and including subframe N, the mobile stationapplies the source TDD configuration. Specifically, the mobile stationapplies the timing relation defined by the source TDD configuration forone or plural PUSCH transmission(s) that are scheduled in response tothe one or plural DCI transmission(s) carrying the respective UL grantreceived during same subframes.

For PUSCH transmissions relating to DCI transmissions that were receivedby the mobile station from and including subframe N+1 onward, the mobilestation applies the target TDD configuration. Specifically, the mobilestation applies the timing relation defined by the target TDDconfiguration for the one or plural PUSCH transmission(s) that arescheduled in response to the one or plural DCI transmission(s) carryingthe respective UL grant received during same subframes.

In particular, due to the application of the target TDD configuration toa PUSCH transmission relating to a DCI transmission received immediatelyafter the TDD UL/DL re-configuration takes effect (i.e. subframe N), theuplink bandwidth utilization within the communication system can beimproved.

According to a third aspect of the invention, a communication between amobile station and a base station in a communication system is specifiedemploying another improved TDD UL/DL re-configuration. The communicationis re-configured from a source TDD configuration to a target TDDconfiguration.

The source and the target uplink/downlink configurations are out of aplurality of TDD configurations. For example, the source and the targetTDD configurations are any one out of the plurality of pre-configuredTDD configurations 0-6.

In the event that the communication between the mobile station and thebase station is to be re-configured for a predetermined subframe N atthe beginning of the subframe, the radio frames before subframe N wherethe re-configuration takes effect are configured based on the source TDDconfiguration, whereas the radio frames from and including subframe Nonward are configured based on the target TDD configuration.

Further, in case the mobile station is to perform Hybrid ARQ-ACKtransmissions in response to Physical Downlink Shared Channel, PDSCH,transmissions, the mobile station performs the HARQ-ACK transmissionsaccording to the following scheme:

For Hybrid ARQ-ACK transmissions that are to be transmitted by themobile station up to and including subframe N−1, the mobile stationapplies the source TDD configuration. Specifically, the mobile stationapplies, during same subframes, the timing relation defined by thesource TDD configuration for one or plural HARQ-ACK transmission(s) thatare to be transmitted in response to the one or plural PDSCHtransmission(s) previously received by the mobile station.

For Hybrid ARQ-ACK transmissions that are to be sent by the mobilestation during subframes N+1 to N+12, the mobile station applies anotherintermediate (i.e. predefined) TDD configuration. Specifically, themobile station applies, during same subframes, the timing relationdefined by the other intermediate (i.e. predefined) TDD configurationfor the one or plural HARQ-ACK transmission(s) that that are to betransmitted in response to the one or plural PDSCH transmission(s)previously received by the mobile station. The other intermediate TDDconfiguration is one of out of the plurality of TDD configurations.

For Hybrid ARQ-ACK transmissions that are to be sent by the mobilestation from and including subframe N+13 onward, the mobile stationapplies the target TDD configuration. Specifically, the mobile stationapplies, during same subframes, the timing relation defined by thetarget TDD configuration for the one or plural HARQ-ACK transmission(s)that that are to be transmitted in response to the one or plural PDSCHtransmission(s) previously received by the mobile station.

In particular, due to the application of the other intermediate (i.e.predefined) TDD configuration to a HARQ-ACK transmissions that are to betransmitted/received immediately after the TDD UL/DL re-configurationtakes effect (i.e. subframe N), the Hybrid ARQ functionality can becontinuously utilized.

According to a first embodiment in line with the first aspect of theinvention, a method is proposed for communicating between a mobilestation and a base station in a communication system. The communicationis re-configured from a source to a target uplink/downlinkconfiguration. The source uplink/downlink configuration is one out of asubset of a plurality of uplink/downlink configurations and the targetuplink/downlink configuration is any one of the plurality ofuplink/downlink configurations. The plurality of uplink/downlinkconfigurations are pre-configured for Time Division Duplex, TDD,communication. In case the communication is to be re-configured for apredetermined subframe N at the beginning of a radio frame, thecommunication system is to perform Physical Uplink Shared Channel,PUSCH, transmissions in response to Downlink Control Information, DCI,transmissions such that: the source uplink/downlink configuration isapplied to PUSCH transmissions relating to DCI transmissions received upto and including subframe N−6; a predefined uplink/downlinkconfiguration is applied to PUSCH transmissions relating to DCItransmissions received during subframes N−5 to N−1; and the targetuplink/downlink configuration is applied to PUSCH transmissions relatingto DCI transmissions received from subframe N onward; wherein thepredefined uplink/downlink configuration is one of out of the pluralityof uplink/downlink configurations.

According to a second embodiment in line with the second aspect of theinvention, a method is suggested for communicating between a mobilestation and a base station in a communication system. The communicationis re-configured from a source to a target uplink/downlinkconfiguration. The source uplink/downlink configuration is a predefinedone out of a plurality of uplink/downlink configurations and the targetuplink/downlink configuration is any one of the plurality ofuplink/downlink configurations. The plurality of uplink/downlinkconfigurations are pre-configured for Time Division Duplex, TDD,communication. In case the communication is to be re-configured for apredetermined subframe N at the beginning of a radio frame, thecommunication system is to perform Physical Uplink Shared Channel,PUSCH, transmissions in response to Downlink Control Information, DCI,transmissions such that: the source uplink/downlink configuration isapplied to PUSCH transmissions relating to DCI transmissions received upto and including subframe N; the target uplink/downlink configuration isapplied to PUSCH transmissions relating to DCI transmissions receivedfrom subframe N+1 onward.

According to a third embodiment in line with the third aspect of theinvention, a method is proposed for communicating between a mobilestation and a base station in a communication system. The communicationis re-configured from a source to a target uplink/downlinkconfiguration. The source and the target uplink/downlink configurationare out of a plurality of uplink/downlink configurations. The pluralityof uplink/downlink configurations are pre-configured for Time DivisionDuplex, TDD, communication. In case the communication is to bere-configured for a predetermined subframe N at the beginning of a radioframe, the communication system is to perform Hybrid ARQ-ACKtransmissions in response to Physical Downlink Shared Channel, PDSCH,transmissions such that: the source uplink/downlink configuration isapplied to Hybrid ARQ-ACK transmissions up to and including subframeN−1; another predefined uplink/downlink configuration is applied toHybrid ARQ-ACK transmissions during subframes N to N+12; and the targetuplink/downlink configuration is applied to Hybrid ARQ-ACK transmissionsfrom subframe N+13 onward; wherein the other predefined uplink/downlinkconfiguration is one of out of the plurality of uplink/downlinkconfigurations.

The third embodiment can be combined with either the first or the secondembodiment.

Further to the first embodiment, a mobile station is suggested forcommunicating with a base station in a communication system. Thecommunication is re-configured from a source to a target uplink/downlinkconfiguration. The source uplink/downlink configuration is one out of asubset of a plurality of uplink/downlink configurations and the targetuplink/downlink configuration is any one of the plurality ofuplink/downlink configurations. The plurality of uplink/downlinkconfigurations are pre-configured for Time Division Duplex, TDD,communication. In case the communication is to be re-configured for apredetermined subframe N at the beginning of a radio frame, the mobilestation is to perform Physical Uplink Shared Channel, PUSCH,transmissions in response to Downlink Control Information, DCI,transmissions such that: the source uplink/downlink configuration isapplied to PUSCH transmissions relating to DCI transmissions received upto and including subframe N−6; a predefined uplink/downlinkconfiguration is applied to PUSCH transmissions relating to DCItransmissions received during subframes N−5 to N−1; and the targetuplink/downlink configuration is applied to PUSCH transmissions relatingto DCI transmissions received from subframe N onward; wherein thepredefined uplink/downlink configuration is one of out of the pluralityof uplink/downlink configurations.

Further to the second embodiment, a mobile station is proposed forcommunicating with a base station in a communication system. Thecommunication is re-configured from a source to a target uplink/downlinkconfiguration. The source uplink/downlink configuration is a predefinedone out of a plurality of uplink/downlink configurations and the targetuplink/downlink configuration is any one of the plurality ofuplink/downlink configurations. The plurality of uplink/downlinkconfigurations are pre-configured for Time Division Duplex, TDD,communication. In the event that the communication is to bere-configured for a predetermined subframe N at the beginning of a radioframe, the mobile station is to perform Physical Uplink Shared Channel,PUSCH, transmissions in response to Downlink Control Information, DCI,transmissions such that: the source uplink/downlink configuration isapplied to PUSCH transmissions relating to DCI transmissions received upto and including subframe N; the target uplink/downlink configuration isapplied to PUSCH transmissions relating to DCI transmissions receivedfrom subframe N+1 onward.

Further to the third embodiment, a mobile station is proposed forcommunicating with a base station in a communication system. Thecommunication is re-configured from a source to a target uplink/downlinkconfiguration. The source and the target uplink/downlink configurationsare out of a plurality of uplink/downlink configurations. The pluralityof uplink/downlink configurations are pre-configured for Time DivisionDuplex, TDD, communication. In case the communication is to bere-configured for a predetermined subframe N at the beginning of a radioframe, the mobile station is to perform Hybrid ARQ-ACK transmissions inresponse to Physical Downlink Shared Channel, PDSCH, transmissions suchthat: the source uplink/downlink configuration is applied to HybridARQ-ACK transmissions up to and including subframe N−1; anotherpredefined uplink/downlink configuration is applied to Hybrid ARQ-ACKtransmissions during subframes N to N+12; and the target uplink/downlinkconfiguration is applied to Hybrid ARQ-ACK transmissions from subframeN+13 onward; wherein the other predefined uplink/downlink configurationis one of out of the plurality of uplink/downlink configurations.

Even further to the first embodiment, a computer readable medium isproposed that stores instructions which, when executed by a processor ofa mobile station, cause the mobile station to communicate with a basestation in a communication system. The communication is re-configuredfrom a source to a target uplink/downlink configuration. The sourceuplink/downlink configuration is one out of a subset of a plurality ofuplink/downlink configurations and the target uplink/downlinkconfiguration is any one of the plurality of uplink/downlinkconfigurations. The plurality of uplink/downlink configurations arepre-configured for Time Division Duplex, TDD, communication. In case thecommunication is to be re-configured for a predetermined subframe N atthe beginning of a radio frame, the mobile station is to performPhysical Uplink Shared Channel, PUSCH, transmissions in response toDownlink Control Information, DCI, transmissions such that: the sourceuplink/downlink configuration is applied to PUSCH transmissions relatingto DCI transmissions received up to and including subframe N−6; apredefined uplink/downlink configuration is applied to PUSCHtransmissions relating to DCI transmissions received during subframesN−5 to N−1; and the target uplink/downlink configuration is applied toPUSCH transmissions relating to DCI transmissions received from subframeN onward; wherein the predefined uplink/downlink configuration is one ofout of the plurality of uplink/downlink configurations.

Even further to the second embodiment, a computer readable medium issuggested that stores instructions which, when executed by a processorof a mobile station, cause the mobile station to communicate with a basestation in a communication system. The communication is re-configuredfrom a source to a target uplink/downlink configuration. The sourceuplink/downlink configuration is a predefined one out of a plurality ofuplink/downlink configurations and the target uplink/downlinkconfiguration is any one of the plurality of uplink/downlinkconfigurations. The plurality of uplink/downlink configurations arepre-configured for Time Division Duplex, TDD, communication. In case thecommunication is to be re-configured for a predetermined subframe N atthe beginning of a radio frame, the mobile station is to performPhysical Uplink Shared Channel, PUSCH, transmissions in response toDownlink Control Information, DCI, transmissions such that: the sourceuplink/downlink configuration is applied to PUSCH transmissions relatingto DCI transmissions received up to and including subframe N; the targetuplink/downlink configuration is applied to PUSCH transmissions relatingto DCI transmissions received from subframe N+1 onward.

Even further to the third embodiment, a computer readable medium isproposed that stores instructions which, when executed by a processor ofa mobile station, cause the mobile station to communicate with a basestation in a communication system. The communication is re-configuredfrom a source to a target uplink/downlink configuration. The sourceuplink/downlink configuration is one out of a subset of a plurality ofuplink/downlink configurations and the target uplink/downlinkconfiguration is any one of the plurality of uplink/downlinkconfigurations. The plurality of uplink/downlink configurations arepre-configured for Time Division Duplex, TDD, communication. In case thecommunication is to be re-configured for a predetermined subframe N atthe beginning of a radio frame, the mobile station is to perform HybridARQ-ACK transmissions in response to Physical Downlink Shared Channel,PDSCH, transmissions such that: the source uplink/downlink configurationis applied to Hybrid ARQ-ACK transmissions up to and including subframeN−1; another predefined uplink/downlink configuration is applied toHybrid ARQ-ACK transmissions during subframes N to N+12; and the targetuplink/downlink configuration is applied to Hybrid ARQ-ACK transmissionsfrom subframe N+13 onward; wherein the other predefined uplink/downlinkconfiguration is one of out of the plurality of uplink/downlinkconfigurations.

BRIEF DESCRIPTION OF THE FIGURES

In the following the invention is described in more detail withreference to the attached figures and drawings.

FIG. 1 shows an exemplary architecture of a 3GPP LTE system,

FIG. 2 shows an exemplary overview of the overall E-UTRAN architectureof 3GPP LTE,

FIG. 3 shows exemplary subframe boundaries on a downlink componentcarrier as defined for 3GPP LTE (as of Release 8/9),

FIG. 4 shows an exemplary downlink resource grid of a downlink slot asdefined for 3GPP LTE (as of Release 8/9),

FIG. 5 shows the seven currently-standardized (static) TDD UL/DLconfigurations 0-6, the respective definitions of the 10 subframes andtheir switch-point periodicity,

FIG. 6 illustrates the HARQ ACK/NACK/DTX feedback timing for the staticTDD configurations 0-6 as defined by 3GPP LTE,

FIG. 7 illustrates Physical Uplink Shared CHannel, PUSCH, transmissiontimings in response to a Downlink Control Information, DCI, transmissionfor the static TDD configurations 0-6 as defined by 3GPP LTE,

FIG. 8 illustrates the structure of a radio frame, being composed of twohalf-frames and 10 subframes, for a 5 ms switch-point periodicity,

FIGS. 9-10 show a sequence of exemplary radio frames for three TDD UL/DLre-configuration operations and their drawbacks,

FIG. 11a illustrates an exemplary TDD UL/DL re-configuration operationincluding the improved PUSCH transmission allocation according to afirst embodiment of the invention,

FIG. 11b illustrates an exemplary TDD UL/DL re-configuration operationincluding the improved HARQ-ACK transmission allocation according to asecond embodiment of the invention, and

FIG. 12 illustrates an exemplary TDD UL/DL re-configuration operationincluding a different realization of the improved PUSCH transmissionallocation according to a third embodiment of the invention.

DETAILED DESCRIPTION OF THE INVENTION

The following paragraphs will describe various embodiments of theinvention. For exemplary purposes only, most of the embodiments areoutlined in relation to a radio access scheme according to 3GPP LTE(Release 8/9) and LTE-A (Release 10/11/12) mobile communication systems,partly discussed in the Technical Background section above.

It should be noted that the invention may be advantageously used, forexample, in a mobile communication system such as 3GPP LTE-A (Release10/11/12) communication systems as described in the Technical Backgroundsection above, but the invention is not limited to its use in thisparticular exemplary communication networks.

In the context of the invention, the terms “source TDD configuration” or“source uplink/downlink configuration” as well as “target TDDconfiguration” or “target uplink/downlink configuration” are used toemphasize the concept of the TDD UL/DL re-configuration. Nonetheless, itshould be clear that the source TDD configuration is not the firstconfiguration that is to be applied for communication between the mobilestation and the base station in the communication system. Similarly, thetarget TDD configuration is also not the last TDD configuration that isto be applied for communication within the communication system.

Specifically, in the context of the invention the terms source andtarget TDD configuration may be construed in the sense that in the eventa TDD UL/DL re-configuration takes effect in subframe N, the source TDDconfiguration is at least applied in the interval [N−k, N−6] where k>=10for the first embodiment and in the interval [N−k, N] where k>=9 in thesecond embodiment. Similarly, the target TDD configuration is at leastapplied in the interval [N, N+j] where j>=4 in the first embodiment and[N+1, N+j] where j>=10 in the second embodiment. Similar considerationsequally apply for the third and fourth embodiment.

In the following, several embodiments of the invention will be explainedin detail. The explanations should not be understood as limiting theinvention, but as mere examples of the invention's embodiments to betterunderstand the invention. A skilled person should be aware that thegeneral principles of the invention as laid out in the claims can beapplied to different scenarios and in ways that are not explicitlydescribed herein. Correspondingly, the following scenarios assumed forexplanatory purposes of the various embodiments shall not limit theinvention as such.

The various embodiments explained for the invention in general refer toTDD configurations and in particular shall provide an improved and moreflexible TDD configuration and related mechanisms/processes.

First Embodiment

In connection with the summary of the invention, it has already beenemphasized that the various embodiments are based on the concept thatfor a TDD UL/DL re-configuration the timing relations relating to DCI toPUSCH and/or to PDSCH to HARQ-ACK are to be applied differently from theTDD radio frame configuration. This distinction between the TDD radioframe configuration and the timing relations is only to take placeduring a short period of time before and/or after the re-configurationtakes effect.

According to the first embodiment, the DCI to PUSCH timing relations areadapted to allow for an advantageous TDD UL/DL re-configuration.Specifically, in this embodiment the DCI to PUSCH timing relations areadapted during a short period of time before the re-configuration takeseffect such that the uplink bandwidth utilization within thecommunication system can be improved.

An exemplary TDD UL/DL re-configuration operation according to the firstembodiment is illustrated in FIG. 11a , which emphasizes the benefits ofthe distinction between the TDD radio frame configuration and the DCI toPUSCH timing relation. The TDD UL/DL re-configuration operation shown inFIG. 11a is based on the example illustrated in FIG. 9a . The example ofFIG. 11 a equally assumes a TDD UL/DL re-configuration from TDDconfiguration 3 to TDD configuration 6. The re-configuration is to takeeffect at subframe 20, being the first subframe of a radio frame.

The first embodiment assumes a communication between a mobile stationand a base station in a communication system. The communication is to bere-configured from a source to a target TDD configuration. For thisfirst embodiment to be applicable, the source TDD configuration is oneout of a subset of a plurality of TDD configurations, and the target TDDconfiguration is any one of the plurality of TDD configurations. Itshall be emphasized that the term “re-configuration” inherently definesthat the source TDD configuration is different from the target TDDconfiguration.

In an advantageous realization, the subset of TDD configurationscorresponds to TDD configurations 1-6, and the plurality of TDDconfigurations corresponds to TDD configurations 0-6. Although in theabove advantageous realization, the TDD configuration 0 appearsdisadvantageous as source TDD configuration for the first embodiment,nonetheless the adapted DCI to PUSCH timing relation may be applied fora TDD UL/DL re-configuration of the first embodiment where the sourceTDD configuration is TDD configuration 0.

For the communication between the mobile station and the base station tobe re-configured, information is distributed within the communicationsystem including the mobile station and the base station. Thedistribution of the information causes the communication between themobile station and the base station to be re-configured for apredetermined subframe N, the subframe N being at the beginning of aradio frame.

According to one exemplary implementation, the subframe N, for which there-configuration takes effect, corresponds to the first subframe in aradio frame. However, according to different exemplary implementations,the subframe N may also correspond to the second, third or fourthsubframe in a radio frame.

In response to one or plural Downlink Control Information, DCI,transmission(s), the corresponding Physical Uplink Shared Channel,PUSCH, transmissions are to be performed by the mobile station accordingto the DCI to PUSCH timing relations defined in this embodiment.Specifically, the term “DCI to PUSCH timing relations” refers to thetiming offset as defined by a TDD configuration index between one orplural DCI transmission(s) and the corresponding PUSCH transmission(s).

First, the source TDD configuration is applied by the mobile terminal toPUSCH transmissions relating to DCI transmissions that were received bythe mobile station up to and including subframe N−6. Specifically, themobile station applies the timing relation defined by the source TDDconfiguration for one or plural PUSCH transmission(s) that are scheduledin response to the one or plural DCI transmission(s) carrying therespective UL grant received during same subframes.

Then, an intermediate (i.e. predefined) TDD configuration is applied bythe mobile terminal to PUSCH transmissions relating to DCI transmissionsthat were received by the mobile station during and including subframeN−5 up to and including subframe N−1. Specifically, the mobile stationapplies the timing relation defined by the intermediate (i.e.predefined) TDD configuration for the one or plural PUSCHtransmission(s) that are scheduled in response to the one or plural DCItransmission(s) carrying the respective UL grant received during samesubframes.

Finally, the target TDD configuration is applied by the mobile terminalto PUSCH transmissions relating to DCI transmissions that were receivedby the mobile station from and including subframe N onward.Specifically, the mobile station applies the timing relation defined bythe target TDD configuration for the one or plural PUSCH transmission(s)that are scheduled in response to the one or plural DCI transmission(s)carrying the respective UL grant received during same subframes.

According to an advantageous implementation, the intermediate (i.e.predefined) TDD configuration to be applied for PUSCH transmissionsrelating to DCI transmissions during subframes N−5 to N−1 is differentfrom the source TDD configuration. In this respect, the Communicationsystem is provided with the possibility to allow application of a TDDconfiguration as intermediate (i.e. predefined) TDD configuration thatprescribes DCI to PUSCH timing relations which mitigate uplink bandwidthlosses resulting from the transition between source and target TDDconfiguration.

According to an advantageous implementation of the first embodiment, theintermediate (i.e. predefined) TDD configuration is TDD configuration 6as defined in FIG. 7. This TDD configuration 6 allows DCI transmissionscarrying UL grants for three subframes of the subsequent radio frame. Inparticular, in TDD configuration 6 a DCI transmission in subframe 5, 6and 9 enables a respective PUSCH transmissions in subframes (5+7)=12,(6+7)=13 and (9+5)=14. In this respect, TDD configuration 6 enablesPUSCH transmissions in all subframes (i.e. subframes 2, 3 and 4) of thefirst half of the subsequent radio frame which can be configured tosupport uplink transmissions (cf. FIG. 5).

Referring to the example shown in FIG. 11a , the TDD configuration 6 isapplied to determine the timing relations of DCI to PUSCH for thesubframes 15-19 (cf. hatched subframes in FIG. 11a ). Specifically, theTDD configuration 6 is applied to PUSCH transmissions relating to DCIsubframes that have been received in subframes 15, 16 and 19 such thatthe TDD configuration 6 prescribes the PUSCH transmissions to be carriedout in subframes 22, 23 and 24 after the TDD UL/DL re-configuration hastaken effect (cf. dash-dotted arrows in FIG. 11a ).

In this respect, the first embodiment allows for the adaptation of theDCI to PUSCH timing relations, namely corresponding to an intermediate(i.e. predefined) TDD configuration, during a short period of timebefore the re-configuration takes effect. Thereby, un-allocatable PUSCHsubframes can be avoided such that the uplink bandwidth utilizationwithin the communication system improves.

Specifically, in the event that TDD configuration 6 is utilized as anintermediate (i.e. predefined) TDD configuration for determining the DCIto PUSCH timing relation of DCI transmissions during subframes N−5 toN−1, all subframes of the first half of the subsequent radio frame canbe allocated for PUSCH transmissions. Specifically, the subsequent radioframe is the first radio frame for which the TDD UL/DL re-configurationtakes effect.

Second Embodiment

In the second embodiment, similar to the first embodiment, the DCI toPUSCH timing relations are adapted to allow for an advantageous TDDUL/DL re-configuration. Specifically, in this embodiment the DCI toPUSCH timing relations are adapted during a short period of time afterthe re-configuration takes effect such that the uplink bandwidthutilization within the communication system can be improved.

Also the second embodiment assumes a communication between a mobilestation and a base station in a communication system. The communicationis to be re-configured from a source to a target TDD configuration. Forthis second embodiment to be applicable, the source TDD configuration isa predefined one out of a plurality of TDD configurations, and thetarget TDD configuration is any one of the plurality of TDDconfigurations. It shall be emphasized that the term “re-configuration”inherently defines that the source TDD configuration is different fromthe target TDD configuration.

In an advantageous realization, the intermediate (i.e. predefined) oneof the plurality of TDD configurations corresponds to TDD configuration0, and the plurality of TDD configurations corresponds to TDDconfigurations 0-6. Although in the above advantageous realization, theTDD configurations 1-6 appear disadvantageous as source TDDconfigurations for the second embodiment, nonetheless the adapted DCI toPUSCH timing relation may be applied for a TDD UL/DL re-configuration ofthe second embodiment where the source TDD configuration is one of TDDconfigurations 1-6.

For the communication between the mobile station and the base station tobe re-configured, information is distributed within the communicationsystem including the mobile station and the base station. Thedistribution of the information causes the communication between themobile station and the base station to be re-configured for apredetermined subframe N, the subframe N being at the beginning of aradio frame.

According to one exemplary implementation, the subframe N, for which there-configuration takes effect, corresponds to the first subframe in aradio frame. However, according to different exemplary implementations,the subframe N may also correspond to the second, third or fourthsubframe in a radio frame.

In response to one or plural Downlink Control Information, DCI,transmission(s), the corresponding Physical Uplink Shared Channel,PUSCH, transmission(s) are to be performed by the mobile stationaccording to the DCI to PUSCH timing relations defined in thisembodiment. Specifically, the term “DCI to PUSCH timing relations”refers to the timing offset as defined by a TDD configuration indexbetween one or plural DCI transmission(s) and the corresponding PUSCHtransmission(s).

First, the source TDD configuration is applied by the mobile terminal toPUSCH transmissions relating to DCI transmissions that are received bythe mobile station up to and including subframe N. Specifically, themobile station applies the timing relation defined by the source TDDconfiguration for one or plural PUSCH transmission(s) that are scheduledin response to the one or plural DCI transmission(s) carrying therespective UL grant received during same subframes.

Then, the target TDD configuration is applied by the mobile terminal toPUSCH transmissions relating to DCI transmissions that are received bythe mobile station from and including subframe N+1 onward. Specifically,the mobile station applies the timing relation defined by the target TDDconfiguration for the one or plural PUSCH transmission(s) that arescheduled in response to the one or plural DCI transmission(s) carryingthe respective UL grant received during same subframes.

Since the TDD UL/DL re-configuration is configured to take effect forthe subframe with the index N at the beginning of a radio frame, it isnot possible for N to correspond to the last subframe in a radio frame.In this respect, it is also not possible that the source TDDconfiguration is applied to PUSCH transmissions relating to DCItransmissions received in one radio frame, and that the target TDDconfiguration is applied to PUSCH transmissions relating to DCItransmissions received in another (i.e. the subsequent) subframe.

In other words, the definition of the subframe N at the beginning of aradio frame prevents the switch between the application of the sourceand of the target TDD configuration to correspond to radio frameboundaries. This would only be the case if the source TDD configurationwas to be applied to PUSCH transmissions relation to DCI transmissionsthat were received up to and including subframe N−1.

Specifically, in the advantageous realization, the application of theTDD configuration 0 for a PUSCH transmission relating to a DCItransmission received in subframe N is particularly advantageous becauseotherwise, the allocation of a PUSCH transmission in subframe 24 couldnot be ensured. As can be readily appreciated from FIG. 7, the TDDconfiguration 0 enables TDD transmissions carrying UL grants that relateto two subframes of the subsequent radio frame. In particular, in TDDconfiguration 0, a DCI transmission in subframe 5 and 6 enables arespective PUSCH transmission in subframes (5+7)=12 and (6+7)=13.However, subframe 14 is also configurable to support PUSCHtransmissions.

In this respect, the TDD configuration 0 is also applied to a PUSCHtransmission relating to a DCI transmission that has been received insubframe N (e.g. subframe 0, 10, 20) such that the PUSCH transmission insubframe N+4 (e.g. subframe 4, 14, 24) becomes possible. In other words,in case TDD configuration 0 is utilized as an intermediate (i.e.predefined) TDD configuration for determining the DCI to PUSCH timingrelation of DCI transmissions during subframes up to and includingsubframe N, all subframes of the first half of the subsequent radioframe that can be allocated for PUSCH transmissions.

Referring to the example shown in FIG. 12, the TDD configuration 0 isapplied to determine the timing relation of DCI to PUSCH for subframe 20(cf. subframe in FIG. 12). Specifically, TDD configuration 0 is appliedto a PUSCH transmission relating to a DCI subframe that has beenreceived in subframe 20; Thus, the TDD configuration 0 prescribes thePUSCH transmission to be carried out in subframe 24 after the TDD UL/DLre-configuration has taken effect (cf. dash-dotted arrow in FIG. 12).

In general, in the first and second embodiment each of the plurality ofTDD configurations determines a timing offset between said one or pluralDCI transmission(s) and the corresponding PUSCH transmission(s). Thistiming offset between one or plural DCI transmission(s) and thecorresponding PUSCH transmission(s) is also denoted as DCI to PUSCHtiming relation throughout the description.

Further, in the first and second embodiment the source TDD configurationspecifies whether a subframe is reserved for downlink transmissions,uplink transmissions, or denotes a special subframe supporting downlinkas well as uplink transmissions, up to and including subframe N−1, andthe target TDD configuration specifies whether a subframe is reservedfor downlink transmissions, uplink transmissions, or denotes a specialsubframe supporting downlink as well as uplink transmissions, fromsubframe N onward. In this respect, the re-configuration of the TDDradio frame configuration takes effect for and including the indicatedsubframe N.

Third Embodiment

In connection with the third embodiment of the invention, it shall beagain emphasized that the various embodiments are based on the conceptthat for a TDD UL/DL re-configuration the timing relations relating toDCI to PUSCH and/or to PDSCH to HARQ-ACK are to be applied differentlyfrom the TDD radio frame configuration. This distinction between the TDDradio frame configuration and the timing relations is only to take placeduring a short period of time before and/or after the re-configurationtakes effect.

According to the third embodiment, the PDSCH to HARQ-ACK timingrelations are adapted to allow for an advantageous TDD UL/DLre-configuration. Specifically, in this embodiment the PDSCH to HARQ-ACKtiming relations are adapted during a short period of time after there-configuration takes effect such that the Hybrid ARQ functionality isconsistently available.

An exemplary TDD UL/DL re-configuration operation according to the thirdembodiment is illustrated in FIG. 11b which emphasizes the benefits ofthe distinction between the TDD radio frame configuration and the PDSCHto HARQ-ACK timing relations. The TDD UL/DL re-configuration operationshown in FIG. 11b is based on the example illustrated in FIG. 9b . Theexample of FIG. 11b equally assumes a TDD UL/DL re-configuration fromTDD configuration 3 to TDD configuration 6. The re-configuration is totake effect at subframe 20 being the first subframe of a radio frame.

The third embodiment assumes a communication between a mobile stationand a base station in a communication system. The communication is to bere-configured from a source to a target TDD configuration. The sourceand the target TDD configuration are any one out of a plurality of TDDconfigurations. It shall be emphasized that the term “re-configuration”inherently defines that the source TDD configuration is different fromthe target TDD configuration.

In an advantageous realization, the source TDD configuration correspondsto one of TDD configurations 0-6, and the target TDD configurationcorresponds to another one of TDD configurations 0-6.

For the communication between the mobile station and the base station tobe re-configured, information is distributed within the communicationsystem including the mobile station and the base station. Thedistribution of the information causes the communication between themobile station and the base station to be re-configured for apredetermined subframe N, the subframe N being at the beginning of aradio frame.

According to one exemplary implementation, the subframe N, for which there-configuration takes effect, corresponds to the first subframe in aradio frame. However, according to different exemplary implementations,the subframe N may also correspond to the second, third or fourthsubframe in a radio frame.

In response to one or plural Physical Downlink Shared CHannel, PDSCH,transmission(s), the related Hybrid ARQ-ACKnowledgement, HARQ-ACKtransmissions are to be performed by the mobile station according to thePDSCH to HARQ-ACK timing relations defined in this embodiment.Specifically, the term “PDSCH to HARQ-ACK timing relations” refers tothe timing offset as defined by a TDD configuration between one orplural PDSCH transmission(s) and the corresponding HARQ-ACKtransmission(s).

First, the source TDD configuration is applied by the mobile station toHybrid ARQ-ACK transmissions up to and including subframe N−1.Accordingly, the mobile station determines based on the source TDDconfiguration for each of the subframes up to and including subframe N−1whether or not one or plural HARQ-ACK transmission(s) have to be carriedout. Specifically, the mobile station determines for which of previousone or plural PDSCH transmission(s) (if any) the source TDDconfiguration indicates HARQ-ACK transmission(s) in the respectivesubframes.

Then, another intermediate (i.e. predefined) TDD configuration isapplied by the mobile station to Hybrid ARQ-ACK transmissions during andincluding subframe N up to and including subframe N+12. Accordingly, themobile station determines, based on the other intermediate (i.e.predefined) TDD configuration for each of the subframes during subframeN to N+12, whether or not one or plural HARQ-ACK transmission(s) have tobe carried out. Specifically, the mobile station determines for which ofprevious one or plural PDSCH transmission(s) (i.e. if there are anyPDSCH transmissions), the other intermediate (i.e. predefined) TDDconfiguration indicates HARQ-ACK transmission(s) in the respectivesubframes.

Finally, the target TDD configuration is applied by the mobile stationto Hybrid ARQ-ACK transmissions from and including subframe N+13 onward.Accordingly, the mobile station determines, based on the target TDDconfiguration for each of the subframes from subframe N+13 onward,whether or not one or plural HARQ-ACK transmission(s) have to be carriedout. Specifically, the mobile station determines for which of previousone or plural PDSCH transmission(s) (i.e. if there are any PDSCHtransmissions), the target TDD configuration indicates HARQ-ACKtransmission(s) in the respective subframes.

According to an advantageous implementation, the other intermediate(i.e. predefined) TDD configuration, to be applied to HARQ-ACKtransmissions during subframes N to N+13, is different from the targetTDD configuration. In this respect, the Communication system is providedwith the possibility to allow application of a TDD configuration asother intermediate (i.e. predefined) TDD configuration that prescribesPDSCH to HARQ-ACK timing relations which makes the Hybrid ARQfunctionality consistently available during the transition from sourceto target TDD configuration.

According to an advantageous implementation of the third embodiment, theother intermediate (i.e. predefined) TDD configuration is TDDconfiguration 5 as defined in FIG. 6. This TDD configuration 5 allowsfor HARQ-ACK transmissions relating to PDSCH transmissions that havebeen received by the mobile terminal in the previous two radio frames.Specifically, in TDD configuration 5, subframe 2 enables combining nineHARQ-ACK transmissions which relate to PDSCH transmissions that werereceived by the mobile terminal 13, 12, 9, 8, 7, 5, 4, 11 and 6subframes earlier, respectively.

Referring to the example shown in FIG. 11b , the TDD configuration 5 isapplied to determine the timing relations of PDSCH to HARQ-ACK forHARQ-transmissions during subframes 20-32 (cf. hatched subframes in FIG.11b ). Specifically, the TDD configuration 5 is applied to HARQ-ACKtransmissions in subframes 22 and 32 such that the TDD configuration 5prescribes the PDSCH transmissions to which the HARQ-ACK transmissionsrelate after the TDD UL/DL re-configuration has taken effect (cf.dash-dotted arrows in FIG. 11b ).

In this respect, the third embodiment allows for the adaptation of thePDSCH to HARQ-ACK timing relations, namely corresponding to anotherintermediate (i.e. predefined) TDD configuration, during a short periodof time before the re-configuration takes effect. Thereby, PDSCHsubframes for which HARQ-ACKs are transmitted can be avoided such thatthe Hybrid ARQ functionality is consistently available.

First Implementation

According to a first implementation of the third embodiment, the otherintermediate (i.e. predefined) TDD configuration is no longer consideredto be a static configuration of the communication system. Instead, theother intermediate (i.e. predefined) TDD configuration, which is to beapplied to HARQ-ACK transmissions during subframes N to N+12, issignaled within the communication system.

Specifically, an information is distributed within the communicationsystem that is indicating which one out of the plurality of TDDconfigurations corresponds to the other intermediate (i.e. predefined)TDD configuration. Upon reception of the information indicating theother intermediate (i.e. predefined) TDD configuration by the mobileterminal, the mobile terminal applies this other intermediate (i.e.predefined) TDD configuration for subsequent TDD UL/DLre-configurations, namely during subframes N to N+12 where subframe Nindicates the subframe from which onward the re-configuration is to takeeffect.

Optionally, the information indicating the other intermediate (i.e.predefined) TDD configuration may be combined with an informationindicating the subframe from which the communication within thecommunication system is to be re-configured.

Second Implementation

In a second implementation of the third embodiment, the effect of pluralHARQ-ACK transmissions for one PDSCH transmissions is considered indetail. As exemplarily illustrated in FIG. 11b , for the PDSCHtransmission in subframes 9 and 10, HARQ-ACK transmissions are effectedin response to the application of the source TDD configuration (i.e. TDDconfiguration 3) and subsequent HARQ-ACK transmissions are effected inresponse to the application of the other intermediate (i.e. predefined)TDD configuration.

Specifically, plural HARQ-ACK transmissions result from a (i.e. one)PDSCH transmission where the mobile terminal determines that the sourceTDD configuration prescribes a HARQ-ACK transmission up to and includingsubframe N−1 relating to the PDSCH transmission, and that the otherintermediate (i.e. predefined) TDD configuration prescribes a HARQ-ACKtransmission during subframes N to N+12 relating to the same PDSCHtransmission.

According to the second implementation the mobile station additionallydetermines which of potentially plural HARQ-ACK transmissions are to becarried out for one PDSCH transmission. In more detail, in response to a(i.e. one) PDSCH transmission, in the event that the application of thesource TDD configuration prescribes a HARQ-ACK transmission up to andincluding subframe N−1 relating to the PDSCH transmission, and where theapplication of the other intermediate (i.e. predefined) TDDconfiguration prescribes a HARQ-ACK transmission during subframes N toN+12 relating to the PDSCH transmission, the mobile node is to onlyperform the HARQ-ACK transmission up to and including subframe N−1; or,alternatively, the mobile node is to only perform the HARQ-ACKtransmission during subframes N to N+12.

Specifically, when the mobile terminal only performs the HARQ-ACKtransmission up to and including subframe N−1 the delay for the HARQ-ACKfeedback can be kept small. Further, the payload resulting form theHARQ-ACK transmissions during subframes N to N+12 can be reduced.

According to an advantageous variation of the second implementation, incase of plural HARQ-ACK transmissions for a (i.e. one) PDSCHtransmission, the mobile station is to perform the HARQ-ACK transmissionup to and including subframe N−1, and additionally is to perform theHARQ-ACK transmission during subframes N to N+12 including a predefinedinformation, e.g. a discontinuous transmission, DTX, information.

In more detail, in response to a (i.e. one) PDSCH transmission, in theevent that the application of the source TDD configuration prescribes aHARQ-ACK transmission up to and including subframe N−1 relating to thePDSCH transmission, and where the application of the other intermediate(i.e. predefined) TDD configuration prescribes a HARQ-ACK transmissionduring subframes N to N+12 relating to the PDSCH transmission, themobile node is to perform the HARQ-ACK transmission up to and includingsubframe N−1; and is to perform the HARQ-ACK transmission duringsubframes N to N+12 including a DTX information.

Third Implementation

A third implementation of the third embodiment focuses on HARQ-ACKtransmissions that are prescribed by the other intermediate (i.e.predefined) TDD configuration, which, however, relate to precedingsubframes that were never reserved for PDSCH transmissions.

As already described in detail with respect to the third embodiment, theother intermediate (i.e. predefined) TDD configuration is applied todetermine for which of the preceding PDSCH transmissions a HARQ-ACKtransmission is to be performed during subframe N to N+12. This iscarried out separately from the TDD radio frame configuration which isspecified by the source TDD configuration up to and including subframeN−1 and by the target TDD configuration from the subframe N onward.

In other words, the other intermediate (i.e. predefined) TDDconfiguration reflects a different TDD radio frame configuration andrefers to different (i.e. more) subframes for PDSCH transmission thanthe source TDD configuration actually reserves.

According to the third implementation, in the event that the applicationof the other intermediate (i.e. predefined) TDD configuration prescribesa Hybrid ARQ-ACK transmission during subframes N to N+12 for at leastone subframe that is configured to only support uplink transmissions,the mobile node is to perform Hybrid ARQ-ACK transmissions duringsubframes N to N+12 only relating to subframes that are configured tosupport downlink transmission; or, alternatively, the mobile terminalperforms a Hybrid ARQ-ACK transmission including predefined information.

Advantageously, the predefined information may indicate that the said atleast one subframe only supports uplink transmissions and does notrelate to a PDSCH transmission.

Further Implementation

In any of the preceding embodiments, the communication between themobile station and the base station may be re-configured for subframe Nbased on the distribution of information indicating the re-configurationwithin the communication system.

The distribution of same information causes the communication betweenthe mobile station and the base station to be re-configured for apredetermined subframe N, the subframe N being at the beginning of aradio frame.

In this respect, in the event that the mobile terminal receivesinformation indicating that the communication between the mobile stationand the base station is to be re-configured, the mobile terminal is toperform the respective TDD UL/DL re-configuration by applying the timingrelations relating to DCI to PUSCH and/or to PDSCH to HARQ-ACKdifferently (i.e. separately) from the TDD radio frame configuration.

Advantageously, the Information indicating the re-configuration is onlyconsidered by the mobile station and/or the base station if it isdistributed within an interval including and after subframe N−14 up toand including subframe N−5, where subframe N indicates when there-configuration is to take effect. In order to reduce the risk offalsely detecting and applying a re-configuration by the mobile station,it is further advantageous if the UE applies a re-configuration only ifthe information indicating the re-configuration is detected multipletimes, e.g. two times, within said interval, and furthermore only if theindicated re-configuration is identical in these multiple times. Forexample, if the probability of falsely detecting a singlere-configuration information amounts to 1%, then the probability offalsely detecting a re-configuration information two times amounts to0.01%. These approaches are particularly beneficial if are-configuration is indicated by an explicit message, i.e. by a signalthat contains at least the target configuration as information.

An alternative method to determine a re-configuration more implicitly isto check for the non-presence (or lack) of uplink transmissions oruplink resource assignments for PUSCH according to the timing for uplinksubframes according to the source UL/DL configuration (or the UL/DLconfiguration indicated by SIB1). For example, referring to FIG. 5 andFIG. 7, the following table shows preferred embodiments how a lack ofPUSCH assignment(s) for a subframe j can indicate a reconfiguration to atarget TDD configuration as a function of the source TDD configuration.In an advanced method, only the lack of PUSCH assignment(s) for thefirst subframe j of a radio frame determines the reconfiguration. Forexample, if the source configuration is 0 and no PUSCH assignment isdetected for subframe 3 of a radio frame, the target configuration isdetermined as configuration 2. A further lack of PUSCH assignment forsubframe 4 of the same radio frame would not further modify the targetconfiguration

Source No PUSCH assignment Determined target configuration detected forsubframe j configuration 0 9 6 0 4 1 0 3 2 1 7 4 1 3 2 2 7 5 3 4 4 3 3 54 3 5 6 7 3 6 4 1 6 3 2

Fourth Embodiment

According to a fourth embodiment, the concept of the invention is alsoapplied to the signaling of Transmit Power Control, TPC, commands. TPCcommands are distributed within the communication system to indicate thetransmit power to be used by a mobile station. Accordingly, uponreceiving a TPC command, the mobile station considers the valuetransmitted therein for future uplink transmission.

In 3GPP LTE, TPC commands are specified to only indicate differentialpower variations of the transmit power to be carried out by the mobileterminal. For example, a TPC command may indicate to a mobile terminalthat it is to ramp-up the transmit power by an included amount or thatthe terminal is to ramp-down the transmit power by another includedamount. In this respect a continuous signaling of TPC commands improvesthe flexibility of power adjustments carried out by the mobile terminal.

It is important to note that the TPC commands may be sent irrespectiveof uplink transmissions to be carried out by the mobile terminal. Inother words, the mobile terminal performs transmit power computationsfor each subframe prior to an actual uplink transmission based on theTPC commands received. Accordingly, one or plural TPC command(s) arereceived and the transmit power evaluated by the mobile terminal for asubframe on a constant basis.

Nevertheless, the TPC commands applicable for a given uplinktransmission can only be transmitted based on pre-configured timingrelations that are comparable to those previously discussed as DCI toPUSCH and/or PDSCH to HARQ-ACK. Specifically, it is distinguishedbetween a TPC command for PUSCH and a TPC command for PUCCH.

The TPC command for PUSCH is included in a DCI transmission carrying anUL grant or in a Transmit Power Control (TPC) command DCI transmission.The DCI transmission including the TPC command for PUSCH is of format0/4 or of format 3/3A and corresponds to the DCI transmission relatingto a PUSCH transmission discussed in connection with the first andsecond embodiment. Nevertheless, since a TPC command for PUSCH may alsobe received and be processed as part of the PUSCH power control via aDCI transmission not scheduling a PUSCH, such as by DCI formats 3 and3A, a different timing relation is defined.

In particular, Table 5.1.1.1-1 defined in 3GPP TS 36.213, Section5.1.1.1 “UE behaviour”, incorporated hereby by reference, defines thetiming relationship between the transmission of a TPC command for PUSCHand the processing thereof as part of the PUSCH power control.Specifically, this TPC to PUSCH timing relation is specified in Table5.1.1.1-1 in reverse subframe direction. In detail, for the PUSCH powercontrol to be performed in subframe i, the mobile terminal refers to aprevious TPC command for PUSCH transmission up to and including subframei−k. In other words, for subframe number i, indicated in the Table5.1.1.1-1, a TPC command for PUSCH transmission that has been received ksubframes prior to the subframe of number i for which the PUSCH powercontrol is to be carried out.

For enabling, during a TDD UL/DL re-configuration, a continuous PUSCHpower control at the mobile terminal, the same considerations of theprevious embodiments are reflected in the following mechanism, which canbe separately performed in case the communication between the mobileterminal and the base station is to be re-configured or can be combinedwith one of the previous embodiments.

According to one variation, it is assumed that a mobile stationcommunicates with a base station in a communication system. Thecommunication is re-configured from a source to a target TDDconfiguration. Further, the source TDD configuration is one out of asubset of a plurality of TDD configurations and the target TDDconfiguration is anyone of the plurality of TDD configurations. Theplurality of TDD configurations are pre-configured for Time DivisionDuplex, TDD, communication. In case the communication is to bere-configured for a predetermined subframe N at the beginning of a radioframe, the mobile station is to perform PUSCH power control in responseto a TPC command for PUSCH transmission according to the followingscheme:

Firstly, the source TDD configuration is applied for performing PUSCHpower control for a subframe relating to a TPC command for PUSCHtransmission received up to and including subframe N−6. Then, anintermediate (i.e. predefined) TDD configuration is applied forperforming PUSCH power control for a subframe relating to a TPC commandfor PUSCH transmission received during subframes N−5 to N−1; andFinally, the target TDD configuration is applied for performing PUSCHpower control for a subframe relating to a TPC command for PUSCHtransmission received from subframe N onward. The intermediate (i.e.predefined) TDD configuration is one of out of the plurality of TDDconfigurations. Advantageously, the intermediate (i.e. predefined) TDDconfiguration is different from the source TDD configuration andpreferably TDD configuration 6.

According to another variation, it is also assumed that a mobile stationcommunicates with a base station in a communication system. Thecommunication is re-configured from a source to a target TDDconfiguration. Further, the source TDD configuration is a predefined oneout of a plurality of TDD configurations and the target TDDconfiguration is anyone of the plurality of TDD configurations. Theplurality of TDD configurations is pre-configured for Time DivisionDuplex, TDD, communication.

In case the communication is to be re-configured for a predeterminedsubframe N at the beginning of a radio frame, the mobile station is toperform PUSCH power control in response to a TPC command for PUSCHtransmission according to the following scheme:

Firstly, the source TDD configuration is applied for performing PUSCHpower control for a subframe relating to a TPC command for PUSCHtransmission received up to and including subframe N. Then, the targetTDD configuration is applied for performing PUSCH power control for asubframe relating to a TPC command for PUSCH transmission received fromsubframe N+1 onward. Advantageously, the source TDD configuration is TDDconfiguration 0.

According to a further variation, it is also assumed that a mobilestation communicates with a base station in a communication system. Thecommunication is re-configured from a source to a target TDDconfiguration. Further, the source and the target TDD configurations areanyone out of a plurality of TDD configurations. The plurality of TDDconfigurations is pre-configured for Time Division Duplex, TDD,communication.

In case the communication is to be re-configured for a predeterminedsubframe N at the beginning of a radio frame, the mobile station is toperform power control adjustments for PUSCH transmissions in response toa TPC command for PUSCH transmission according to the following scheme:

Firstly, the source TDD configuration is applied for performing PUSCHpower control for a subframe relating to a TPC command for PUSCHtransmission received up to and including subframe N. Then, the targetTDD configuration is applied for performing PUSCH power control for asubframe relating to a TPC command for PUSCH transmission received fromsubframe N+1 onward. Advantageously, the source TDD configuration is TDDconfiguration 0.

Firstly, for power control adjustments for PUSCH transmissions insubframes up to and including subframe N+1, the source TDD configurationis applied for determining in which subframe the corresponding TPCcommand is included. Then, for power control adjustments for PUSCHtransmissions in subframes N+2 to N+4, an intermediate (i.e. predefined)TDD configuration is applied for determining in which subframe thecorresponding TPC command is included; and Finally, for power controladjustments for PUSCH transmissions in subframe N+5 onward, the targetTDD configuration is applied for determining in which subframe thecorresponding TPC command is included. Alternatively, the last subframewhere the source TDD configuration is applied may also be N−1 or N andthe first subframe where the intermediate (i.e. predefined) TDDconfiguration is applied may respectively be N or N+1. The intermediate(i.e. predefined) TDD configuration is one of out of the plurality ofTDD configurations. Advantageously, the intermediate (i.e. predefined)TDD configuration is different from the source TDD configuration andpreferably TDD configuration 6.

The TPC command for PUCCH is included in a DCI transmission for PDSCHassignments or in a Transmit Power Control (TPC) command DCItransmission. The DCI transmission including the TPC command for PUCCHis of format 1A/1B/1D/1/2A/2/2B/2C/2D and corresponds to the DCItransmission relating to a PDSCH transmission discussed in connectionwith the third embodiment. Nevertheless, since a TPC command for PUCCHmay also be received and be processed as part of the PUCCH power controlvia a DCI transmission not scheduling a PUCCH a different timingrelation is defined.

In particular, the timing relation for PUCCH is defined in 3GPP TS36.213, Section 5.1.2.1 “UE behaviour”, incorporated hereby byreference, referencing Table 10.1.3.1-1 of TS 36.213, Section 10.1.3.1“TDD HARQ-ACK procedure for one configured serving cell” as timingrelationship between the transmission of a TPC command for PUCCH and theprocessing thereof as part of the PUCCH power control. Specifically, theTPC to PUCCH timing relation is specified to correspond to the PDSCH toHARQ-ACK timing relation. This correspondence between timing relationsresults from the fact that DCI transmissions, including the TPC commandfor PUCCH, are effected in the same subframe as the PDSCH transmissionsto which the HARQ-ACK transmissions relate.

In this respect, for enabling, during a TDD UL/DL re-configuration, acontinuous PUCCH power control at the mobile terminal, the sameconsiderations of the previous embodiments are reflected in thefollowing mechanism, which can be separately performed in case thecommunication between the mobile terminal and the base station is to bere-configured or can be combined with one of the previous embodiments.

According to yet another variation, it is assumed that a mobile stationcommunicates with a base station in a communication system. Thecommunication is re-configured from a source to a target TDDconfiguration.

Further, the source TDD configuration is a predefined one out of aplurality of TDD configurations and the target TDD configuration isanyone of the plurality of TDD configurations. The plurality of TDDconfigurations is pre-configured for Time Division Duplex, TDD,communication.

In case the communication is to be re-configured for a predeterminedsubframe N at the beginning of a radio frame, the mobile station is toperform PUCCH power control in response to one or plural TPC command(s)for PUCCH transmission according to the following scheme:

Firstly, the source TDD configuration is applied to perform PUCCH powercontrol up to and including subframe N−1. Then, another intermediate(i.e. predefined) TDD configuration is applied to perform PUCCH powercontrol during subframes N to N+12. Finally, the target TDDconfiguration is applied to perform PUCCH power control from subframeN+13 onward; wherein the other intermediate (i.e. predefined) TDDconfiguration is one of out of the plurality of TDD configurations.Advantageously, the intermediate (i.e. predefined) TDD configuration isdifferent from the target TDD configuration and preferably TDDconfiguration 5.

Hardware and Software Implementation of the Invention

Another embodiment of the invention relates to the implementation of theabove described various embodiments using hardware and software. In thisconnection the invention provides an user equipment (mobile station) andan eNodeB (base station). The user equipment is adapted to perform themethods described herein.

It is further recognized that the various embodiments of the inventionmay be implemented or performed using computing devices (processors). Acomputing device or processor may for example be general purposeprocessors, digital signal processors (DSP), application specificintegrated circuits (ASIC), field programmable gate arrays (FPGA) orother programmable logic devices, etc. The various embodiments of theinvention may also be performed or embodied by a combination of thesedevices.

Further, the various embodiments of the invention may also beimplemented by means of software modules, which are executed by aprocessor or directly in hardware. Also, a combination of softwaremodules and a hardware implementation may be possible. The softwaremodules may be stored on any kind of computer readable storage media,for example RAM, EPROM, EEPROM, flash memory, registers, hard disks,CD-ROM, DVD, etc.

It should be further noted that the individual features of the differentembodiments of the invention may, individually or in arbitrarycombination, be subject matter to another invention.

It would be appreciated by a person skilled in the art that numerousvariations and/or modifications may be made to the present invention asshown in the specific embodiments without departing from the spirit orscope of the invention as broadly described. The present embodimentsare, therefore, to be considered in all respects to be illustrative andnot restrictive.

1-32. (canceled)
 33. A mobile station for communicating with a basestation in a communication system, the communication being re-configuredfrom a source to a target uplink/downlink configuration, wherein thesource uplink/downlink configuration is one out of a subset of aplurality of uplink/downlink configurations and the targetuplink/downlink configuration is any one of the plurality ofuplink/downlink configurations, the plurality of uplink/downlinkconfigurations being pre-configured for Time Division Duplex, TDD,communication, wherein: in the event that the communication is to bere-configured for a predetermined subframe N at the beginning of a radioframe, the mobile station is to perform Physical Uplink Shared Channel,PUSCH, transmissions in response to Downlink Control Information, DCI,transmissions such that: the source uplink/downlink configuration isapplied to PUSCH transmissions relating to DCI transmissions received upto and including subframe N−6; a predefined uplink/downlinkconfiguration is applied to PUSCH transmissions relating to DCItransmissions received during subframes N−5 to N−1; and the targetuplink/downlink configuration is applied to PUSCH transmissions relatingto DCI transmissions received from subframe N onward; wherein thepredefined uplink/downlink configuration is one of out of the pluralityof uplink/downlink configurations.
 34. The mobile station according toclaim 33 wherein the predefined uplink/downlink configuration isdifferent from the source uplink/downlink configuration.
 35. The mobilestation according to claim 33, wherein: the plurality of uplink/downlinkconfigurations are uplink/downlink configurations 0-6; the sourceuplink/downlink configuration is one out of the subset ofuplink/downlink configurations 1-6; and the predefined uplink/downlinkconfiguration is uplink/downlink configuration
 6. 36. A mobile stationfor communicating with a base station in a communication system, thecommunication being re-configured from a source to a targetuplink/downlink configuration, wherein the source uplink/downlinkconfiguration is a predefined one out of a plurality of uplink/downlinkconfigurations and the target uplink/downlink configuration is any oneof the plurality of uplink/downlink configurations, the plurality ofuplink/downlink configurations being pre-configured for Time DivisionDuplex, TDD, communication, wherein: in the event that the communicationis to be re-configured for a predetermined subframe N at the beginningof a radio frame, the mobile station is to perform Physical UplinkShared Channel, PUSCH, transmissions in response to Downlink ControlInformation, DCI, transmissions such that: the source uplink/downlinkconfiguration is applied to PUSCH transmissions relating to DCItransmissions received up to and including subframe N; the targetuplink/downlink configuration is applied to PUSCH transmissions relatingto DCI transmissions received from subframe N+1 onward.
 37. The mobilestation according to claim 36, wherein: the plurality of uplink/downlinkconfigurations are uplink/downlink configurations 0-6; the sourceuplink/downlink configuration is uplink/downlink configuration
 0. 38.The mobile station according to claim 33, wherein each of the pluralityof uplink/downlink configurations determines a timing offset betweensaid DCI transmissions and the corresponding PUSCH transmissions. 39.The mobile station according to claim 33, wherein the sourceuplink/downlink configuration denotes whether a subframe is reserved fordownlink transmissions, uplink transmissions, or denotes a specialsubframe supporting downlink as well as uplink transmissions, up to andincluding subframe N−1, and wherein the target uplink/downlinkconfiguration denotes whether a subframe is reserved for downlinktransmissions, uplink transmissions, or denotes a special subframesupporting downlink as well as uplink transmissions, from subframe Nonward.
 40. The mobile station according to claim 33, wherein in theevent that an information is distributed within the communication systemwhich indicates that the communication between a mobile station and abase station is to be re-configured, and where the information isdistributed within an interval including and after subframe N−14 up toand including subframe N−5, the distribution of the information causesthe communication to be re-configured for the predetermined subframe N,wherein N is a subframe at the beginning of a radio frame.
 41. Themobile station according to claim 33, wherein the mobile station is toperform Hybrid ARQ-ACK transmissions in response to Physical DownlinkShared Channel, PDSCH, transmissions such that: the sourceuplink/downlink configuration is applied to Hybrid ARQ-ACK transmissionsup to and including subframe N−1; another predefined uplink/downlinkconfiguration is applied to Hybrid ARQ-ACK transmissions duringsubframes N to N+12; and the target uplink/downlink configuration isapplied to Hybrid ARQ-ACK transmissions from subframe N+13 onward;wherein the other predefined uplink/downlink configuration is one of outof the plurality of uplink/downlink configurations.
 42. The mobilestation according to claim 41, wherein the other predefineduplink/downlink configuration is different from the targetuplink/downlink configuration.
 43. The mobile station according to claim41, wherein: the other predefined uplink/downlink configuration isuplink/downlink configuration
 5. 44. The mobile station according toclaim 41, wherein within the communication system an information isdistributed that indicates which one out of the plurality ofuplink/downlink configurations corresponds to the other predefineduplink/downlink configuration to be applied to Hybrid ARQ-ACKtransmissions during subframes N to N+12.
 45. The mobile stationaccording to claim 41, wherein each of the plurality of uplink/downlinkconfigurations determines a timing offset between said PDSCHtransmission and the corresponding Hybrid ARQ-ACK transmission.
 46. Themobile station according to claim 41, wherein, in response to a PhysicalDownlink Shared Channel, PDSCH, transmission, in the event that thesource uplink/downlink configuration is applied, and where same sourceuplink/downlink configuration prescribes a Hybrid ARQ-ACK transmissionup to and including subframe N−1, the Hybrid ARQ-ACK transmissionrelating to the PDSCH transmission, and in the event that the otherpredefined uplink/downlink configuration is applied, and where sameother predefined uplink/downlink configuration prescribes a HybridARQ-ACK transmission during subframes N to N+12, the Hybrid ARQ-ACKtransmission relating to the PDSCH transmission, the mobile station isto only perform the Hybrid ARQ-ACK transmission up to and includingsubframe N−1; or, alternatively, the mobile station is to only performthe Hybrid ARQ-ACK transmission during subframes N to N+12.
 47. Themobile station according to claim 41, wherein, in the event that theother predefined uplink/downlink configuration is applied, and wheresame other predefined uplink/downlink configuration prescribes a HybridARQ-ACK transmission during subframes N to N+12 for at least onesubframe that is configured to only support uplink transmissions, saidat least one subframe being within an interval of subframe N−11 up toand including subframe N−1, the mobile station is to perform HybridARQ-ACK transmissions during subframes N to N+12 only relating tosubframes that are configured to support downlink transmission; or,alternatively, the mobile station performs a Hybrid ARQ-ACK transmissionincluding predefined information for the at least one subframe that isconfigured to only support uplink transmissions indicating that the saidat least one subframe only supports uplink transmissions and does notrelate to a PDSCH transmission.
 48. A method for communicating between amobile station and a base station in a communication system, thecommunication being re-configured from a source to a targetuplink/downlink configuration; wherein the source uplink/downlinkconfiguration is one out of a subset of a plurality of uplink/downlinkconfigurations and the target uplink/downlink configuration is any oneof the plurality of uplink/downlink configurations, the plurality ofuplink/downlink configurations being pre-configured for Time DivisionDuplex, TDD, communication, wherein: in case the communication is to bere-configured for a predetermined subframe N at the beginning of a radioframe, the communication system is to perform Physical Uplink SharedChannel, PUSCH, transmissions in response to Downlink ControlInformation, DCI, transmissions such that: the source uplink/downlinkconfiguration is applied to PUSCH transmissions relating to DCItransmissions received up to and including subframe N−6; a predefineduplink/downlink configuration is applied to PUSCH transmissions relatingto DCI transmissions received during subframes N−5 to N−1; and thetarget uplink/downlink configuration is applied to PUSCH transmissionsrelating to DCI transmissions received from subframe N onward; whereinthe predefined uplink/downlink configuration is one of out of theplurality of uplink/downlink configurations.
 49. The method according toclaim 48, wherein the predefined uplink/downlink configuration isdifferent from the source uplink/downlink configuration.
 50. The methodaccording to claim 48, wherein: the plurality of uplink/downlinkconfigurations are uplink/downlink configurations 0-6; the sourceuplink/downlink configuration is one out of the subset ofuplink/downlink configurations 1-6; and the predefined uplink/downlinkconfiguration is uplink/downlink configuration
 6. 51. The methodaccording to claim 48, wherein the source uplink/downlink configurationdenotes whether a subframe is reserved for downlink transmissions,uplink transmissions, or denotes a special subframe supporting downlinkas well as uplink transmissions, up to and including subframe N−1; andwherein the target uplink/downlink configuration denotes whether asubframe is reserved for downlink transmissions, uplink transmissions,or denotes a special subframe supporting downlink as well as uplinktransmissions, from subframe N onward.
 52. The method according to claim48, wherein in the event that an information is distributed within thecommunication system which indicates that the communication between amobile station and a base station is to be re-configured, and where theinformation is distributed within an interval including and aftersubframe N−14 up to and including subframe N−5, the distribution of theinformation causes the communication to be re-configured for thepredetermined subframe N, wherein N is a subframe at the beginning of aradio frame.